Silicone hydrogels comprising N-alkyl methacrylamides and contact lenses made thereof

ABSTRACT

The present invention relates to silicone hydrogels exhibiting desired combinations of physical and mechanical properties, formed from a reactive monomer mixture comprising at least one N-alkyl methacrylamide, and at least one silicone-containing component. These silicone hydrogels may also contain hydrophilic components, crosslinking agents and toughening monomers. These silicone hydrogels are useful in preparing biomedical devices, ophthalmic lenses, and contact lenses.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/609,088, filed May 31, 2017, which claims priority to U.S.Provisional Patent Application No. 62/358,967, filed Jul. 6, 2016, whichis incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to silicone hydrogels derived fromreactive monomer mixtures comprising N-alkyl methacrylamides, andsilicone-containing components, and displaying surprising combinationsof physical and mechanical properties including modulus. These siliconehydrogels are suitable for use in a number of fields including medicaldevices, ophthalmic devices, and contact lenses.

BACKGROUND

Soft contact lenses are based upon hydrogels. Many users find softcontact lenses comfortable enough to wear all day. There are two mainclasses of soft contact lens materials, conventional soft contact lenseswhich are formed from hydrogels containing no silicone, and siliconehydrogels. Conventional and silicone hydrogels have moduli ranging fromabout 20 psi to about 300 psi, which allows the lenses to conform to theshape of the eye. These modulus levels can require manufacturers toproduce contact lenses having a large number of optical powers andconfigurations.

Silicone hydrogels generally have higher moduli than conventionalhydrogels with values ranging from about 50 psi to about 300 psi.Silicone hydrogel contact lenses displaying moduli greater than about150 psi may decrease patient comfort and increase certain mechanicaladverse events. Nonetheless, even at these higher moduli, siliconehydrogel contact lenses still substantially conform to the shape of theeye requiring a large number of lens designs to fit the patientpopulation.

Toughening agents such as isobornyl methacrylate, methyl methacrylateand crosslinkers are known to increase the modulus of contact lenses.However, they generally detrimentally impact other mechanical propertiesof the lens such as elongation.

U.S. Pat. Nos. 4,182,822 and 4,343,927, disclose silicone hydrogels madefrom reactive mixtures of amide monomers, including N-alkylmethacrylamides, short chain polysiloxanylalkyl methacrylates, andoptionally other monomers. U.S. Pat. No. 5,298,533 discloses thatconventional hydrogels (those with no silicone content) prepared fromN-methyl methacrylamide are less hydrolytically stable than those madefrom N, N-dimethyl acrylamide. None of these patents disclose siliconehydrogel formulations with polysiloxane containing components havingfour or more polysiloxane repeating units or silicone hydrogels havingthe surprising balance of properties disclosed herein.

Kodaira et al in the Polymer Journal Vol. 20, No. 11, pp 1021-1029(1988) disclosed the effects of solvent on the copolymer reactivityratios of N-methyl acrylamide or N-methyl methacrylamide with methylmethacrylate.

Shea et al in Macromolecules Vol. 23, No. 21, pp 4497-4507 (1990)reported the synthesis of highly cross-linked polyacrylamides andpolymethacrylamides, including those made from N-methyl methacrylamideand various bis-methacrylamide cross-linking agents. Poly(N-methylmethacrylamide) was also prepared.

Various N-substituted methacrylamides have been used to make a varietyof non-hydrogel copolymers, including copolymerization of methylmethacrylate with N-methyl, N-cyclohexyl, and N-isobornylmethacrylamides (Chen et al in the Journal of Polymer Science Vol. 82,pp 400-405 (2001)); copolymerization of tert-butyl methacrylate withN-octyl, N-ethyl, N-cyclohexyl, and N-benzyl methacrylamides, which uponthermal treatment generate substituted poly(methacrylimides) foams(Ritter el al in Macromolecules Vol. 36, pp 318-322 (2003)); thesynthesis of homo-polymers from N-phenyl, N-4-methoxyphenyl, andN-4-bromophenyl methacrylamide (Kuo et al in Polymer Vol. 52, pp2600-2608 (2011)).

Schrooten et al in Macromol. Chem. Phys. Vol. 214, pp 2283-2294 (2013)studied the propagation kinetics of the radical polymerization of N,N-dimethyl acrylamide, N-methylmethacrylamide, and methacrylamide inaqueous solution. The propagation rate coefficients decreased withmonomer concentration in part because of concomitant changes in hydrogenbonding and dipole-dipole effects. This reference also disclosed that N,N-dimethyl methacrylamide does not undergo radical homo-polymerization.None of these printed publications from the scientific literaturedisclosed silicone hydrogels with N-alkyl methacrylamides. Some reportedhigh glass transition temperatures for polymers made from N-alkylmethacrylamides, while others reported on the polymerization kinetics ofN-alkyl methacrylamides, highlighting the effects of solvent onreactivity ratios.

US862662 discloses hybrid soft contact lenses where both the central andperipheral portions are formed from hydrous, soft materials havingYoung's modulus between 435 psi and 14,503 psi and between 29 psi and435 psi, respectively. The hydrous soft materials may be formed fromstyryl siloxane monomers and hydrophilic monomers, including(meth)acrylamide monomers. However, N-alkyl methacrylamide monomers arenot disclosed.

For patients with astigmatism, soft contact lenses must be rotationallystabilized in order for the optical correction to be effective in allhead positions. Such stabilization is usually accomplished by the use ofstabilization zones on the posterior side of the contact lens that limitrotation. Alternatively, astigmatic masking lenses having a centralportion of the lens which vaults over the cornea, thereby creating aspace between the corneal surface and the lens, have been developed.Tear film fills that space and masks the astigmatism. Current maskinglenses which have sufficient stiffness in the central region are eitherundesirably thick, or are incompatible with the hydrogel materials usedin the periphery.

SUMMARY OF THE INVENTION

The present invention relates to compositions, including siliconehydrogels formed from reactive mixtures comprising, consisting andconsisting essentially of a silicon-containing component and at leastone N-alkyl methacrylamide monomer.

The present invention relates to silicone hydrogels having a modulus ofat least about 1000 psi and a water content of at least about 10%,formed from a reactive mixture comprising at least one N-alkylmethacrylamide and at least one silicone-containing component.

The present invention relates to non-ionic silicone hydrogels having amodulus of about 140 to about 2000 psi and a water content of about 20to about 50%, formed from a reactive mixture comprising at least oneN-alkyl methacrylamide and at least one silicone containing component.

The present invention relates to silicone hydrogels having a modulus ofabout 150 psi to about 200,000 psi and a water content of about 10 toabout 50%, formed from a reactive mixture comprising at least oneN-alkyl methacrylamide, about 5 to about 15 wt % at least onecrosslinking component, and at least one silicone containing componentselected from compounds of Formulae I through V:

wherein R¹ is a hydrogen atom or methyl; Z is selected from O, N, S orNCH₂CH₂O; when Z═O or S, R² is not required; wherein j is a whole numberbetween 1 and 20; q is up to 50, or 5 to 30 or 10-25; and n¹ and n² arebetween 4 to 100; 4 to 50; or 4 to 25; n³ is 1-50, 1-20, or 1-10;

wherein R² is H or is a linear, branched, or cyclic alkyl groupcontaining one to eight carbon atoms (or 3 to 8 carbon atoms), any ofwhich may be further substituted with at least one hydroxy group, andwhich may be optionally substituted with amide, ether, and combinationsthereof;

wherein R³ is a substituted or unsubstituted C₁₋₆, C₁₋₄ or C₂₋₄ alkylenesegment such as (CH₂)_(r), wherein each methylene group may optionallybe independently substituted with ethers, amines, carbonyls,carboxylates, carbamates and combinations thereof; or an oxyalkylenesegment such as (OCH₂)_(k) and k is a whole number from one to three, orwherein R³ may be a mixture of alkylene and oxyalkylene segments and thesum of r and k is between 1 and 9;

wherein each R⁴ is independently a linear, branched, or cyclic alkylgroup containing between one and six carbon atoms, a linear, branched,or cyclic alkoxy group containing between one and six carbon atoms, alinear or branched polyethyleneoxyalkyl group, a phenyl group, a benzylgroup, a substituted or un-substituted aryl group, a fluoroalkyl group,a partially fluorinated alkyl group, a perfluoroalkyl group, a fluorineatom, or combinations thereof;

wherein R⁵ is a substituted or un-substituted linear or branched alkylgroup having 1 to eight carbon atoms, or 1 to 4 carbon atoms, or methylor butyl; or an aryl group, any of which may be substituted with one ormore fluorine atoms.

The present invention relates to silicone hydrogels formed from areactive mixture comprising at least one N-alkyl methacrylamide, atleast one silicone containing component and at least about 2 wt %, or atleast 5-15 wt % at least one crosslinking component.

The present invention relates to silicone hydrogels having a modulus ofabout 20,000 psi to about 200,000 psi and a water content of about 10 toabout 40%, formed from a reactive mixture comprising

-   -   (a) at least one N-alkyl methacrylamide,    -   (b) at least one crosslinking component    -   (c) at least one bulky siloxane-containing component selected        from the group consisting of tris(trimethylsiloxy)silylstyrene,        3-tris(trimethylsiloxy)silylpropyl methacrylate,        N-[3-tris(trimethylsiloxy)silyl]-propyl acrylamide,        2-hydroxy-3-[3-methyl-3,3-di(trimethylsiloxy)silylpropoxy]-propyl        methacrylate, and other bulky silicone monomers, such as those        in Formulae VI through XIV, wherein each R⁶ is independently        linear, branched, or cyclic alkyl groups containing between one        and eight carbon atoms, or are trimethylsiloxy groups:

The present invention relates to silicone hydrogels formed from areactive mixture comprising

-   -   a) at least one N-alkyl methacrylamide;    -   b) at least one hydroxyl-containing silicone containing        component;    -   c) at least one wetting agent;    -   d) at least one hydroxyalkyl monomer, and    -   e) at least one cross-linking agent.

The present invention relates to composite contact lenses comprising acentral region and a peripheral region wherein the central regioncomprises a first silicone hydrogel formed from a reaction mixturecomprising at least one N-alkyl methacrylamide and at least onesilicone-containing component and the peripheral region comprising asecond silicone hydrogel exhibiting a lower modulus than the centralregion.

The present invention relates to processes for making a compositecontact lens, comprising:

-   -   (a) dosing into a first mold a first silicone hydrogel        formulation hydrogel formed from a reaction mixture comprising        at least one N-alkyl methacrylamide and at least one        silicone-containing components,    -   (b) partially curing the first silicone hydrogel formulation        into a gel,    -   (c) dosing a second silicone hydrogel formulation into the first        mold    -   (d) allowing time for the second silicone hydrogel formulation        to imbibe into the gel,    -   (e) placing a second mold on top of the first mold, and    -   (f) fully curing the combination to form the composite contact        lens.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a micrograph of a composite lens prepared according to Example57 showing the vaulting gap between the contact lens and the artificialcorneal surface.

DETAILED DESCRIPTION

It is to be understood that the invention is not limited to the detailsof construction or process steps set forth in the following description.The invention is capable of other embodiments and of being practiced orbeing carried out in various ways using the teaching herein.

It has been found that silicone hydrogels formed by polymerizing N-alkylmethacrylamides with at least one silicone-containing component andadditional optional components including cross-linking agents,hydrophilic monomers, wetting agents, and toughening agents providesilicone hydrogels which display surprising combinations of properties,including high moduli at desirable water contents. This balance ofproperties is particularly surprising as the same effects are not seenin formulations where structurally similar amides such as acrylamides,such as N,N-dimethlyacrylamide, methacrylamide or methacrylamides whereboth N substituents are either H or alkyl are used with thesilicone-containing component(s).

With respect to the terms used in this disclosure, the followingdefinitions are provided. The polymer definitions are consistent withthose disclosed in the Compendium of Polymer Terminology andNomenclature, IUPAC Recommendations 2008, edited by: Richard G. Jones,Jaroslav Kahovec, Robert Stepto, Edward S. Wilks, Michael Hess, TatsukiKitayama, and W. Val Metanomski.

As used herein, the term “about” refers to a range of +/−5% of thenumber that is being modified. For example, the phrase “about 10” wouldinclude both 9.5 and 10.5.

The term “(meth)” designates optional methyl substitution. Thus, a termsuch as “(meth)acrylate” denotes both methacrylate and acrylateradicals.

Wherever chemical structures are given, it should be appreciated thatalternatives disclosed for the substituents on the structure may becombined in any combination. Thus, if a structure contained substituentsR* and R**, each of which contained three lists of potential groups, 9combinations are disclosed. The same applies for combinations ofproperties.

When a subscript, such as “n” in the generic formula [***]_(n), is usedto depict the number of repeating units in a polymer's chemical formula,the formula should be interpreted to represent the number averagemolecular weight of the macromolecule.

A “macromolecule” is an organic compound having a molecular weight ofgreater than 1500, and may be reactive or non-reactive.

A “polymer” is a macromolecule of repeating chemical units linkedtogether into a chain or network structure and is composed of repeatingunits derived from the monomers and macromers included in the reactivemixture.

A “homopolymer” is a polymer made from one monomer or macromer; a“copolymer” is a polymer made from two or more monomers, macromers or acombination thereof; a “terpolymer” is a polymer made from threemonomers, macromers or a combination thereof. A “block copolymer” iscomposed of compositionally different blocks or segments. Diblockcopolymers have two blocks. Triblock copolymers have three blocks. “Combor graft copolymers” are made from at least one macromer.

A “repeating unit” or “repeating chemical unit” is the smallestrepeating group of atoms in a polymer that result from thepolymerization of monomers and macromers.

A “biomedical device” is any article that is designed to be used whileeither in or on mammalian tissues or fluids, and preferably in or onhuman tissue or fluids. Examples of these devices include but are notlimited to wound dressings, sealants, tissue fillers, drug deliverysystems, coatings, adhesion prevention barriers, catheters, implants,stents, sutures and ophthalmic devices such as intraocular lenses andcontact lenses. The biomedical devices may be ophthalmic devices, suchas contact lenses, including contact lenses made from siliconehydrogels.

“Individual” includes humans and vertebrates.

“Ocular surface” includes the surface and glandular epithelia of thecornea, conjunctiva, lacrimal gland, accessory lacrimal glands,nasolacrimal duct and meibomian gland, and their apical and basalmatrices, puncta and adjacent or related structures, including eyelidslinked as a functional system by both continuity of epithelia, byinnervation, and the endocrine and immune systems.

“Ophthalmic device” refers to any device which resides in or on the eyeor any part of the eye, including the ocular surface. These devices canprovide optical correction, cosmetic enhancement, vision enhancement,therapeutic benefit (for example as bandages) or delivery of activecomponents such as pharmaceutical and nutriceutical components, or acombination of any of the foregoing. Examples of ophthalmic devicesinclude, but are not limited to, lenses and optical and ocular inserts,including, but not limited to punctal plugs and the like. “Lens”includes soft contact lenses, hard contact lenses, hybrid contactlenses, intraocular lenses, and overlay lenses. The ophthalmic devicemay comprise a contact lens.

“Contact lens” refers to a structure, an ophthalmic device that can beplaced on the cornea of an individual's eye. The contact lens mayprovide corrective, cosmetic, therapeutic benefit, including woundhealing, delivery of drugs or neutraceuticals, diagnostic evaluation ormonitoring, or UV blocking and visible light or glare reduction, or acombination thereof. A contact lens can be of any appropriate materialknown in the art, and can be a soft lens, a hard lens, or a hybrid lenscontaining at least two distinct portions with different properties,such as modulus, water content, light absorbing characteristics orcombinations thereof.

The biomedical devices, ophthalmic devices, and lenses of the presentinvention may be comprised of silicone hydrogels. These siliconehydrogels typically contain a silicone component and/or hydrophobic andhydrophilic monomers that are covalently bound to one another in thecured device.

“Silicone hydrogel contact lens” refers to a contact lens comprising atleast one silicone hydrogel material. Silicone hydrogel contact lensesgenerally have increased oxygen permeability compared to conventionalhydrogels. Silicone hydrogel contact lenses use both their water andpolymer content to transmit oxygen to the eye.

A “polymeric network” is cross-linked macromolecule that can swell butcannot dissolve in solvents, because the polymeric network isessentially one macromolecule. “Hydrogel” or “hydrogel material” refersto a polymeric network that contains water in an equilibrium state.Hydrogels generally contain at least about 10 wt. % water.

“Conventional hydrogels” refer to polymeric networks made from monomerswithout any siloxy, siloxane or carbosiloxane groups. Conventionalhydrogels are prepared from monomeric mixtures predominantly containinghydrophilic monomers, such as 2-hydroxyethyl methacrylate (“HEMA”),N-vinyl pyrrolidone (“NVP”), N, N-dimethylacrylamide (“DMA”), or vinylacetate. U.S. Pat. Nos. 4,436,887, 4,495,313, 4,889,664, 5,006,622,5,039,459, 5,236,969, 5,270,418, 5,298,533, 5,824,719, 6,420,453,6,423,761, 6,767,979, 7,934,830, 8,138,290, and 8,389,597 disclose theformation of conventional hydrogels. Commercially available hydrogelformulations include, but are not limited to, etafilcon, polymacon,vifilcon, genfilcon, lenefilcon, hilafilcon, nesofilcon, and omafilcon,including all of their variants.

“Silicone hydrogel” refers to a hydrogel obtained by copolymerization ofat least one silicone-containing component with at least one hydrophiliccomponent. Hydrophilic components may also include non-reactivepolymers. Each of the silicone-containing components and the hydrophiliccomponents may be a monomer, macromer or combination thereof. Asilicone-containing component contains at least one siloxane orcarbosiloxane group.

Examples of commercially available silicone hydrogels includebalafilcon, acquafilcon, lotrafilcon, comfilcon, delefilcon, enfilcon,fanfilcon, formofilcon, galyfilcon, senofilcon, narafilcon, falcon II,asmofilcon A, samfilcon, riofilcon, stenficlon, somofilcon, as well assilicone hydrogels as prepared in U.S. Pat. Nos. 4,659,782, 4,659,783,5,244,981, 5,314,960, 5,331,067, 5,371,147, 5,998,498, 6,087,415,5,760,100, 5,776,999, 5,789,461, 5,849,811, 5,965,631, 6,367,929,6,822,016, 6,867,245, 6,943,203, 7,247,692, 7,249,848, 7,553,880,7,666,921, 7,786,185, 7,956,131, 8,022,158, 8,273,802, 8,399,538,8,470,906, 8,450,387, 8,487,058, 8,507,577, 8,637,621, 8,703,891,8,937,110, 8,937,111, 8,940,812, 9,056,878, 9,057,821, 9,125,808,9,140,825, 9,156,934, 9,170,349, 9,244,196, 9,244,197, 9,260,544,9,297,928, 9,297,929 as well as WO 03/22321, WO 2008/061992, and US2010/048847. These patents, as well as all other patents disclosed inthis paragraph, are hereby incorporated by reference in their entireties

“Silicone-containing component” refers to a monomer, macromer,prepolymer, crosslinker, initiator, additive, or polymer that containsat least one silicon-oxygen bond, in the form of siloxane [—Si—O—Si]group or carbosiloxane group. Examples of silicone-containing componentsinclude, but are not limited to, silicone macromers, prepolymers, andmonomers.

Examples of silicone macromers include, but are not limited to,polydimethylsiloxane methacrylated with pendant hydrophilic groups.Examples of silicone-containing components which are useful in thisinvention may be found in U.S. Pat. Nos. 3,808,178, 4,120,570,4,136,250, 4,153,641, 4,740,533, 5,034,461, 5,962,548, 5,244,981,5,314,960, 5,331,067, 5,371,147, 5,760,100, 5,849,811, 5,962,548,5,965,631, 5,998,498, 6,367,929, 6,822,016, 5,070,215, 8,662,663,7,994,356, 8,772,422, 8,772,367, EP080539 and WO2014/123959.

“Reactive mixture” and “reactive monomer mixture” refer to the mixtureof components (both reactive and non-reactive) which are mixed togetherand when subjected to polymerization conditions, form the siliconehydrogels and lenses of the present invention. The reactive mixturecomprises reactive components such as monomers, macromers, prepolymers,cross-linkers, initiators, diluents, and additional components such aswetting agents, release agents, dyes, light absorbing compounds such asUV absorbers, pigments, dyes and photochromic compounds, any of whichmay be reactive or non-reactive but are capable of being retained withinthe resulting biomedical device, as well as active components such aspharmaceutical and neutraceutical compounds, and any diluents. It willbe appreciated that a wide range of additives may be added based uponthe biomedical device which is made, and its intended use.Concentrations of components of the reactive mixture are given in weight% of all components in the reaction mixture, excluding diluent. Whendiluents are used their concentrations are given as weight % based uponthe amount of all components in the reaction mixture and the diluent.

“Monomer” is a molecule having non-repeating functional groups, whichcan undergo chain growth polymerization, and in particular, free radicalpolymerization. Some monomers have di-functional impurities that can actas cross-linking agents. “Macromers” are linear or branched polymershaving a repeating structure and at least one reactive group that canundergo chain growth polymerization. Monomethacryloxypropyl terminatedmono-n-butyl terminated polydimethylsiloxane (molecular weight=500-1500g/mol) (mPDMS) and mono-(2-hydroxy-3-methacryloxypropyl)-propyl etherterminated mono-n-butyl terminated polydimethylsiloxane (molecularweight=500-1500 g/mol) (OH-mPDMS) are referred to as macromers.

“Reactive components” are the components in the reactive mixture whichbecome part of the structure of the polymeric network of the resultingsilicone hydrogel, by covalent bonding, hydrogen bonding or theformation of an interpenetrating network. Diluents and processing aidswhich do not become part of the structure of the polymer are notreactive components. Typically, the chemical structure of the macromeris different than the chemical structure of the target macromolecule,that is, the repeating unit of the macromer's pendent group is differentthan the repeating unit of the target macromolecule or its mainchain.

“Polymerizable” means that the compound comprises at least one reactivegroup which can undergo chain growth polymerization, such as freeradical polymerization. Examples of reactive groups include themonovalent reactive groups listed below. “Non-polymerizable” means thatthe compound does not comprises such a polymerizable group.

“Monovalent reactive groups” are groups that can undergo chain growthpolymerization, such as free radical and/or cationic polymerization.Non-limiting examples of free radical reactive groups include(meth)acrylates, styrenes, vinyl ethers, (meth)acrylamides,N-vinyllactams, N-vinylamides, O-vinylcarbamates, O-vinylcarbonates, andother vinyl groups. In one embodiment, the free radical reactive groupscomprise (meth)acrylate, (meth)acrylamide, N-vinyl lactam, N-vinylamide,and styryl functional groups, or (meth)acrylates, (meth)acrylamides, andmixtures of any of the foregoing.

Examples of the foregoing include substituted or unsubstitutedC₁₋₆alkyl(meth)acrylates, C₁₋₆alkyl(meth)acrylamides, C₂₋₁₂alkenyls,C₂₋₁₂alkenylphenyls, C₂₋₁₂alkenylnaphthyls, C₂₋₆alkenylphenylC₁₋₆alkyls, where suitable substituents on said C₁₋₆ alkyls includeethers, hydroxyls, carboxyls, halogens and combinations thereof.

Other polymerization routes such as living free radical and ionicpolymerization can also be employed. The device-forming monomers mayform hydrogel copolymers. For hydrogels, the reactive mixture willtypically include at least one hydrophilic monomer.

Hydrophilic components are those which yield a clear single phase whenmixed with deionized water at 25° C. at a concentration of 10 wt. %.

“Interpenetrating polymer networks” or “IPNs” are polymers comprisingtwo or more polymeric networks which are at least partially interlacedon a molecular scale, but not covalently bonded to each other and cannotbe separated unless chemical bonds are broken.

“Semi-interpenetrating polymer networks” or “semi-IPNs” are polymercomprising one or more polymer network(s) and one or more linear orbranched polymer(s) characterized by the penetration on a molecularscale of at least one of the networks by at least some of the linear orbranched chains.

A “cross-linking agent” is a di-functional or multi-functional componentwhich can undergo free radical polymerization at two or more locationson the molecule, thereby creating branch points and a polymeric network.Common examples are ethylene glycol dimethacrylate, tetraethylene glycoldimethacrylate, trimethylolpropane trimethacrylate, methylenebisacrylamide, triallyl cyanurate, and the like.

The silicone hydrogels of the present invention are formed from reactivemixtures comprising (a) at least one N-alkyl methacrylamide monomer, (b)at least one silicone-containing component, and (e) at least onecross-linking agent. The N-alkyl methacrylamide monomer has thestructure shown in Formula XV:

wherein R⁷ is selected from linear, branched, or cyclic alkyl groupscontaining one to eight carbon atoms, benzyl or phenyl, any of which maybe un-substituted or substituted with additional functional groups suchas hydroxyl, amino, and the like.

R⁷ may also be selected from the group consisting of unsubstituted C₁-C₄alkyl groups. When R⁷ is methyl, the N-alkyl methacrylamide monomer isN-methyl methacrylamide (NMMA).

The N-alkyl methacrylamide monomer may be present in the reactivemixture in concentrations between about 1 and about 50 weight percent,about 5 to about 50, about 7 to about 30, about 7 to about 25 or about 7to about 20 wt %, based upon all reactive components. It has beensurprisingly found that hydrogels made from reactive mixtures comprisingat least one N-alkyl methacrylamide monomer and at least one siliconecontaining component display significantly increased modulus, whilestill retaining water content values of greater than 10% or 15% water.The modulus values can range up to 200,000 psi. Despite theirsurprisingly increased modulus, the silicone hydrogels of the presentinvention are not brittle, and have acceptable % elongation valuesgreater than 5%, or greater than 10%. These materials may be used tocreate hybrid contact lenses, with rigid centers which retain theirshape when placed on eye, instead of vaulting over the cornea. Thiscreates a stiffer central optic zone relative to the peripheral zone ofthe contact lens. Stiffness is the modulus of the material, E,multiplied by the cube of thickness, t: Et³.

For contact lenses, as a lens gets thicker, especially beyond about 150or 200 microns, lens awareness increases. Thus, when creating a hybridlens, it may be desirable use materials having moduli greater than about1,000, 10,000 or 100,000. The at least one N-alkyl methacrylamidemonomer and siloxane groups on the at least one silicone containingcomponent appear to interact with each other to create hydrogels havingincreased modulus values compared to formulations without both the atleast one N-alkyl methacrylamide monomer and at least one siliconecontaining component.

The silicone-containing component may be a monomer or macromer and maycomprise at least one monovalent reactive group and at least onesiloxane group. The silicone-containing components may have at leastfour repeating siloxane units, which may be any of the groups definedbelow.

The silicone-containing component may also contain at least one fluorineatom. The silicone-containing component may be selected from thepolydisubstituted siloxane macromer of Formula XVI

wherein at least one R⁸ is a monovalent reactive group, and theremaining R⁸ are independently selected from monovalent reactive groups,monovalent alkyl groups, or monovalent aryl groups, any of the foregoingwhich may further comprise functionality selected from hydroxy, amino,oxa, carboxy, alkyl carboxy, alkoxy, amido, carbamate, carbonate,halogen or combinations thereof; fluoroalkyl alkyl or aryl groups;partially fluorinated alkyl or aryl groups; halogens; linear, branchedor cyclic alkoxy or aryloxy groups; linear or branchedpolyethyleneoxyalkyl groups, polypropyleneoxyalkyl groups, orpoly(ethyleneoxy-co-propyleneoxyalkyl groups; and monovalent siloxanechains comprising between 1-100 siloxane repeat units which may furthercomprise functionality selected from alkyl, alkoxy, hydroxy, amino, oxa,carboxy, alkyl carboxy, alkoxy, amido, carbamate, halogen orcombinations thereof; and wherein n is 0 to 500 or 0 to 200, or 0 to100, or 0 to 20, where it is understood that when n is other than 0, nis a distribution having a mode equal to a stated value.

In Formula XVI from one to three R⁸ may comprise monovalent reactivegroups. Suitable monovalent alkyl and aryl groups include unsubstitutedand substituted monovalent linear, branched or cyclic C₁ to C₁₆ alkylgroups, or unsubstituted monovalent C₁ to C₆ alkyl groups, such assubstituted and unsubstituted methyl, ethyl, propyl, butyl, substitutedor unsubstituted C₆-C₁₄ aryl groups, or a substituted or un-substitutedC₆ aryl group, wherein the substituents include amido, ether, amino,halo, hydroxyl, carboxyl, carbonyl groups; or a phenyl or benzyl group,combinations thereof and the like.

When one R⁸ is a monovalent reactive group, the additional siliconecontaining compounds may be selected from the polydisubstituted siloxanemacromer of Formulae I or II; the styryl polydisubstituted siloxanemacromer of Formula III or IV; or the carbosilane of Formula V:

wherein R¹ is a hydrogen atom or methyl; Z is selected from O, N, S orNCH₂CH₂O; when Z═O or S, R² is not required; wherein j is a whole numberbetween 1 and 20; q is up to 50, 5 to 30 or 10-25; and n¹ and n² arebetween 4 to 100; 4 to 50; or 4 to 25; n³ is 1-50, 1-20, or 1-10;

wherein R² is H or is a linear, branched, or cyclic alkyl groupcontaining one to eight carbon atoms (or 3 to 8 carbon atoms), any ofwhich may be further substituted with at least one hydroxy group, andwhich may be optionally substituted with amide, ether, and combinationsthereof;

wherein R³ is a substituted or unsubstituted C₁₋₆, C₁₋₄ or C₂₋₄ alkylenesegment such as (CH₂)_(r), wherein each methylene group may optionallybe independently substituted with ethers, amines, carbonyls,carboxylates, carbamates and combinations thereof; or an oxyalkylenesegment (OCH₂)_(k) and k is a whole number from one to three, or whereinR³ may be a mixture of alkylene and oxyalkylene segments and the sum ofr and k is between 1 and 9;

wherein each R⁴ is independently a linear, branched, or cyclic alkylgroup containing between one and six carbon atoms, a linear, branched,or cyclic alkoxy group containing between one and six carbon atoms, alinear or branched polyethyleneoxyalkyl group, a phenyl group, a benzylgroup, a substituted or un-substituted aryl group, a fluoroalkyl group,a partially fluorinated alkyl group, a perfluoroalkyl group, a fluorineatom, or combinations thereof;

wherein R⁵ is a substituted or un-substituted linear or branched alkylgroup having 1 to eight carbon atoms, or 1 to 4 carbon atoms, or methylor butyl; or an aryl group, any of which may be substituted with one ormore fluorine atoms.

Non-limiting examples of polysiloxane macromers includemono-methacryloxypropyl terminated mono-n-butyl terminatedpolydimethylsiloxanes (mPDMS) as shown in Formula XVII wherein n isbetween 3 and 15; mono-methacryloxypropyl terminated mono-n-alkylterminated polydimethylsiloxanes, mono-n-alkyl terminated, polydimethyl,polyethylene glycol siloxanes as shown in Formulae XVIII and XXIIIwherein n is between 4-100, 4 and 20, or between 3 and 15; n¹ and n² arebetween 4 to 100, 4 to 50, or 4 to 25; n³ is 1-50, 1-20, or 1-10; R¹ ishydrogen or methyl group; and R⁵ may be C₁-C₄ alkyl or methyl or butyl;and macromers having the chemical structures as shown in Formulae XXIVthrough XXVI, wherein n is between 4-100, 4 and 20, or between 3 and 15;n¹ and n² are between 4 to 100, 4 to 50, or 4 to 25; n³ is 1-50, 1-20,or 1-10; R² is H or is a linear, branched, or cyclic alkyl groupcontaining one to eight carbon atoms, any of which may be furthersubstituted with at least one hydroxy group, and which may be optionallysubstituted with amide, ether, and combinations thereof; and R⁵ may beC₁-C₄ alkyl or methyl or butyl.

Examples of suitable mono(meth)acryloxyalkylpolydisubstituted siloxanesinclude mono(meth)acryloxypropyl terminated mono-n-butyl terminatedpolydimethylsiloxane, mono(meth)acryloxypropyl terminated mono-n-methylterminated polydimethylsiloxane, mono(meth)acryloxypropyl terminatedmono-n-butyl terminated polydiethylsiloxane, mono(meth)acryloxypropylterminated mono-n-methyl terminated polydiethylsiloxane,mono(meth)acrylamidoalkylpolydialkylsiloxanes mono(meth)acryloxyalkylterminated mono-alkyl polydiarylsiloxanes, and mixtures thereof.

In Formula XVI, when n is zero, one or more R⁸ may comprise a monovalentreactive group, two or more R⁸ comprise tris(tri-C₁₋₄alkyl-siloxysilane)groups, monovalent siloxane chains comprising between 1-100, 1-10 or 1-5siloxane repeat units which may further comprise functionality selectedfrom alkyl, alkoxy, hydroxy, amino, oxa, carboxy, alkyl carboxy, alkoxy,amido, carbamate, halogen or combinations thereof; and the remaining R⁸are selected from monovalent alkyl groups having 1 to 16, 1 to 6 or 1-4carbon atoms. Non-limiting examples of silicone components include,3-methacryloxypropyltris(trimethylsiloxy)silane (TRIS),3-methacryloxypropylbis(trimethylsiloxy)methylsilane, and3-methacryloxypropylpentamethyl disiloxane.

The number of siloxane repeating units, n, may also be 2 to 50, 3 to 25,or 3 to 15; wherein at least one terminal R⁸ comprises a monovalentreactive group and the remaining R⁸ are selected from monovalent alkylgroups having 1 to 16 carbon atoms, or from monovalent alkyl groupshaving 1 to 6 carbon atoms. Silicone-containing compounds may alsoinclude those where n is 3 to 15, one terminal R⁸ comprises a monovalentreactive group, the other terminal R⁸ comprises a monovalent alkyl grouphaving 1 to 6 carbon atoms and the remaining R⁸ comprise monovalentalkyl group having 1 to 3 carbon atoms. Non-limiting examples ofsilicone components include monomethacryloxypropyl n-butyl terminatedpolydimethylsiloxanes (M_(n)=800-1000), (mPDMS, as shown in XVII).

Formula XVI may also include compounds where n is 5 to 400 or from 10 to300, both terminal R⁸ comprise monovalent reactive groups and theremaining R⁸ are independently of one another selected from monovalentalkyl groups having 1 to 18 carbon atoms which may have ether linkagesbetween carbon atoms and may further comprise halogen.

One to four R⁸ in Formula XVI may comprise a vinyl carbonate or vinylcarbamate of Formula XXVII:

wherein Y denotes O—, S— or NH—; R¹ denotes a hydrogen atom or methyl.

The silicone-containing vinyl carbonate or vinyl carbamate monomersspecifically include:1,3-bis[4-(vinyloxycarbonyloxy)but-1-yl]tetramethyl-di siloxane;3-(vinyloxycarbonylthio) propyl-[tris(trimethylsiloxy)silane];3-[tris(trimethylsiloxy)silyl] propyl allyl carbamate;3-[tris(trimethylsiloxy)silyl] propyl vinyl carbamate;trimethylsilylethyl vinyl carbonate; trimethylsilylmethyl vinylcarbonate, and the crosslinking agent of Formula XXVIII.

Where biomedical devices with moduli below about 200 psi are desired,only one R⁸ comprises a monovalent reactive group and no more than twoof the remaining R⁸ groups comprise monovalent siloxane groups.

Another suitable silicone-containing macromer is compound of FormulaXXIX in which the sum of x and y is a number in the range of 10 to 30.The silicone containing macromer of Formula XXIX is formed by thereaction of fluoroether, hydroxy-terminated polydimethylsiloxane,isophorone diisocyanate and isocyanatoethylmethacrylate.

The non-hydroxyl containing silicone-containing component may beselected from non-hydroxyl containing acrylamide silicones of U.S. Pat.No. 8,415,405. Other silicone components suitable for use in thisinvention include those described is WO 96/31792 such as macromerscontaining polysiloxane, polyalkylene ether, diisocyanate,polyfluorinated hydrocarbon, polyfluorinated ether and polysaccharidegroups. Another class of suitable silicone-containing componentsincludes silicone-containing macromers made via GTP, such as thosedisclosed in U.S. Pat. Nos. 5,314,960, 5,331,067, 5,244,981, 5,371,147,and 6,367,929. U.S. Pat. Nos. 5,321,108, 5,387,662, and 5,539,016describe polysiloxanes with a polar fluorinated graft or side grouphaving a hydrogen atom attached to a terminal difluoro-substitutedcarbon atom. US 2002/0016383 describes hydrophilic siloxanylmethacrylates containing ether and siloxanyl linkages and crosslinkablemonomers containing polyether and polysiloxanyl groups. Any of theforegoing polysiloxanes can also be used as the silicone-containingcomponent in this invention.

The non-hydroxyl containing silicone component may be selected from thegroup consisting of monomethacryloxypropyl terminated, mono-n-alkylterminated linear polydisubstituted siloxane;methacryloxypropyl-terminated linear polydisubstituted siloxane; andmixtures thereof.

The non-hydroxyl containing silicone component may also be selected frommonomethacrylate terminated, C₁-C₄ alkyl terminated, linearpolydimethylsiloxanes; and mixtures thereof.

In some instances, the non-hydroxyl functionalized silicone-containingcomponent may be used in amounts up to about 10 wt %. Examples includethose selected from mPDMS of Formula XXIII where R⁵ is methyl or butyl,compounds of Formulae XIX through XXVI and the macromers shown inFormula XXX or XXXI where n is n is 1-50 and m is 1-50, 1-20 or 1-10:

Specific examples of silicone containing crosslinkers includebismethacryloxypropyl polydimethyl siloxane, wherein n may be 4-200, or4-150, and the following compounds of Formulae XXXII-XXXVII; wherein n¹and n² are independently selected from 4 to 100; 4 to 50; or 4 to 25; n³is 1-50, 1-20 or 1-10, m is 1-100, 1-50, 1-20 or 1-10, and q is up to50, 5-30 or 10-25;

wherein R¹ is a hydrogen atom or methyl; Z is selected from O, N, S orNCH₂CH₂O; when Z═O or S, R² is not required;

wherein R² is H or is a linear, branched, or cyclic alkyl groupcontaining one to eight carbon atoms, any of which may be furthersubstituted with at least one hydroxy group, and which may be optionallysubstituted with amide, ether, and combinations thereof;

wherein each R⁴ is independently a linear, branched, or cyclic alkylgroup containing between one and six carbon atoms, a linear, branched,or cyclic alkoxy group containing between one and six carbon atoms, alinear or branched polyethyleneoxyalkyl group, a phenyl group, a benzylgroup, a substituted or un-substituted aryl group, a fluoroalkyl group,a partially fluorinated alkyl group, a perfluoroalkyl group, a fluorineatom, or combinations thereof.

The non-hydroxyl containing silicone component may have an averagemolecular weight of from about 400 to about 4000 Daltons.

When Z is O, the silicone containing component may be amono-methacryloxypropyl terminated mono-n-butyl terminatedpolydimethylsiloxanes (mPDMS) as shown in Formula XVII wherein n isbetween 3 and 15; mono-methacryloxypropyl terminated mono-n-alkylterminated polydimethylsiloxanes as shown in Formula XVIII wherein n isbetween 3 and 15; R¹ is a hydrogen or methyl group; and R⁵ is a linear,branched, or cyclic alkyl group containing between 1 and 8 carbon atoms;and macromers having the chemical structures as shown in Formulae Xthrough XIII wherein n is between 4 and 20, or between 3 and 15, 3-30,3-25, 3-20 or 3-15.

When Z is N, further examples of polysiloxane macromers includemono(meth)acrylamidoalkylpolydialkylsiloxanes may be selected from thosedisclosed in U.S. Pat. No. 8,415,405, and those shown in FormulaeXXXVIII, mono(meth)acrylamidoalkyl polydimethylsiloxanes, such as thosein Formulae XXXIX-XLII, wherein n is between 4 and 20, or between 3 and15, 3-30, 3-25, 3-20 or 3-15;

wherein R¹ is a hydrogen or methyl group;

wherein R² is H or is a linear, branched, or cyclic alkyl groupcontaining one to eight carbon atoms, any of which may be furthersubstituted with at least one hydroxy group, and which may be optionallysubstituted with amide, ether, and combinations thereof;

wherein each R⁴ is independently a linear, branched, or cyclic alkylgroup containing between one and six carbon atoms, a linear, branched,or cyclic alkoxy group containing between one and six carbon atoms, alinear or branched polyethyleneoxyalkyl group, a phenyl group, a benzylgroup, a substituted or un-substituted aryl group, a fluoroalkyl group,a partially fluorinated alkyl group, a perfluoroalkyl group, a fluorineatom, or combinations thereof;

wherein R⁵ is a substituted or un-substituted linear or branched alkylgroup having 1 to eight carbon atoms, or 1 to 4 carbon atoms, or methylor butyl; or an aryl group, any of which may be substituted with one ormore fluorine atoms; and N-(2,3-dihydroxypropane)-N′-(propyltetra(dimethylsiloxy) dimethylbutylsilane)acrylamide:

Examples of styryl monomers include tris(trimethylsiloxy)silyl styrene.Examples of styryl macromers are shown below in chemical formulae XLIVthrough XLIX, wherein n is between 4 and 20, or between 3 and 15, 3-30,3-25, 3-20 or 3-15.

The length of the silicone chain may have an impact on the modulus ofthe resulting silicone hydrogel and may be adjusted along with the othercomponents of the reactive mixture to achieve the desired balance ofphysical and mechanical properties. For instance, the amounts of NMMAand the length of the silicone chain may be chosen to attain a watercontent of the silicone hydrogel that moderates stiffness and increaseselongation to break concurrently. As the polydialkylsiloxane chainlength increases, modulus will decrease and elongation to break willincrease. Polydialkylsiloxane chain lengths between 1 and 20, 1 and 15,3-30, 3-25, 3-20 or 3-15 may be selected.

The silicone-containing component may further includesilicone-containing monomers with branched siloxane groups. Examplesinclude tris(trimethylsiloxy)silylstyrene (Styryl-TRIS),3-tris(trimethylsiloxy)silylpropyl methacrylate (TRIS),N-[3-tris(trimethylsiloxy)silyl]-propyl acrylamide (TRIS-Am, FormulaXI), 2-hydroxy-3-[3-methyl-3,3-di(trimethylsiloxy)silylpropoxy]-propylmethacrylate (SiMAA, Formula XXII), and other bulky silicone monomers,such as those in Formulae VI through XIV.

The aforementioned macromers have methacrylate, acrylamide, ormethacylamide reactive groups. These reactive groups may be replacedwith any other reactive group capable of undergoing free radicalpolymerization, such as acrylates, styrenes, vinyl ethers,N-vinyllactams, N-vinylamides, N-vinylimides, N-vinylureas,O-vinylcarbamates, O-vinylcarbonates, and other vinyl compounds. Wheremoduli greater than about 5000 psi are desired, monomers and macromerswith styryl reactive groups are beneficially included.

Alternative silicone-containing components suitable for use includethose described in WO 96/31792 and U.S. Pat. Nos. 5,314,960, 5,331,067,5,244,981, 5,371,147, 6,367,929, U.S. Pat. Nos. 5,321,108, 5,387,662,5,539,016, 6,867,245, and others will be apparent to one skilled in theart

Hydroxyl-Containing Silicone Component

The silicone containing component may also comprise one or morehydroxyl-containing silicone component. Hydroxyl-containing siliconecomponents may help to compatibilize high concentrations of siliconecontaining components with hydrophilic components, including polymerichydrophilic components, and silicone components having bulky siloxanegroups or longer chains of repeating siloxane units. Hydroxyl-containingsilicone components include hydroxyl containing silicone monomers andmacromers. The Hydroxyl-containing silicone components may have 4 to200, 4-100 or 4-20 siloxane repeating units and may be monofunctional ormultifunctional.

Hydroxyl-containing silicone components having 4 polydisubstitutedsiloxane repeating units in the siloxane chain are not a distributionand have four repeating units in each monomer. For allhydroxyl-containing silicone components having more than fourpolydisubstituted siloxane repeating units in the siloxane chain thenumber of repeating units is a distribution, with the peak of thedistribution centered around the listed number of repeat units.

Examples of hydroxyl-containing silicone monomers include propenoicacid-2-methyl-2-hydroxy-3-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]-1-disiloxanyl]propoxy]propylester (“SiGMA”, Formula and2-hydroxy-3-methacryloxypropyloxypropyl-tris(trimethylsiloxy)silane, andcompounds of Formula IX.

The hydroxyl-containing silicone components may be selected frommonofunctional hydroxyl substituted poly(disubstituted siloxane)s ofFormula L:

wherein Z is selected from O, N, S or NCH₂CH₂O, when Z is O or S R² isnot present; R¹ is independently H or methyl; R² is H or is a linear,branched, or cyclic alkyl group containing one to eight carbon atoms,any of which may be further substituted with at least one hydroxy group,and which may be optionally substituted with amide, ether, andcombinations thereof; R⁴ is independently a linear, branched, or cyclicalkyl group containing one to eight carbon atoms, any of which may befurther substituted with at least one hydroxy group, and which may beoptionally substituted with amide, ether, and combinations thereof; orR⁴ may be independently selected from methyl, ethyl or phenyl, or may bemethyl; n is the number of siloxane units and is from 4 to 8 for thefirst monofunctional hydroxyl substituted poly(disubstituted siloxane)monomer; and R⁵ is selected from straight or branched C₁ to C₈ alkylgroups, which may be optionally substituted with one or more hydroxyl,amide, ether, and combinations thereof. R⁵ may be straight or branchedC₄ alkyl, either of which may optionally be substituted with hydroxyl,or may be methyl.

Examples of monofunctional hydroxyl containing silicone componentsinclude mono-(2-hydroxy-3-methacryloxypropyl)-propyl ether terminatedmono-n-butyl terminated polydimethylsiloxanes (OH-mPDMS) as shown inFormula LI wherein n is between 4 and 30, 4-8 or 10-20; andpolydimethylsiloxanes having the chemical structures as shown inFormulae LII through LVIII, wherein Z is selected from O, N, S orNCH₂CH₂O; when Z═O or S, R² is not required; wherein n is between 4 and30, 4-8 or 10-20; wherein n¹ n², and n³ are independently between 4 to100; 4 to 50; 4 to 25; wherein R¹ is a hydrogen or methyl group;

wherein R² is H or is a linear, branched, or cyclic alkyl groupcontaining one to eight carbon atoms, any of which may be furthersubstituted with at least one hydroxy group, and which may be optionallysubstituted with amide, ether, and combinations thereof;

wherein R⁵ is selected from straight or branched C₁ to C₈ alkyl groups,which may be optionally substituted with one or more hydroxyl, amide,ether, polyhydroxyl groups selected from straight or branched C₁ to C₈groups having a formula of C_(f)H_(g)(OH)_(h) wherein f=1-8 and g+h=2f+1and cyclic C₁ to C₈ groups having a formula of C_(f)H_(g)(OH)_(h)wherein f=1-8 and g+h=2f−1, and combinations thereof; or R⁵ may beselected from methyl, butyl or hydroxyl substituted C₂-C₅ alkyl,including hydroxyl ethyl, hydroxyl propyl, hydroxyl butyl, hydroxylpentyl and 2,3-dihydroxypropyl, and polycarbosiloxanes of FormulaeLVII-LVIII where a between 4-100 or 4-8 for the firsthydroxyl-containing silicone component and R¹ and R⁵ are as definedabove.

The hydroxyl-containing silicone component may also be selected frommultifunctional hydroxyl substituted, poly(disubstituted siloxane) ofFormula LIX having 10 to 500, or 10 to 200, or 10 to 100 siloxanerepeating units, and mixtures thereof:

wherein in Formula LIX, Z is selected from O, N, S or NCH₂CH₂O; whereinR¹ is independently a hydrogen atom or methyl group; for Z═O and S, R²is not required;

wherein R² is H or is a linear, branched, or cyclic alkyl groupcontaining one to eight carbon atoms, any of which may be furthersubstituted with at least one hydroxy group, and which may be optionallysubstituted with amide, ether, and combinations thereof;

wherein R⁹, R¹⁰, R¹¹, R¹², R¹³ are independently selected from the groupconsisting of a hydrogen atom or any of the substituents defined for R¹⁴and R¹⁵;

wherein R¹⁴ and R¹⁵ are independently selected from the group consistingof a linear, branched, or cyclic alkyl group containing one to eightcarbon atoms, any of which may be further substituted with at least onehydroxy group, amido, ether, amino, carboxyl, carbonyl groups andcombinations; a linear or branched alkyleneoxy group, specificallyethyleneoxy groups, [CH₂CH₂O]p wherein p is between 1 and 200, or 1 and100, or 1 and 50, or 1 and 25, or 1 and 20, optionally substituted withone or more hydroxyl, amino, amido, ether, carbonyl, carboxyl, andcombinations thereof; a C₁-C₆ linear or branched fluoroalkyl groupsoptionally substituted with one or more hydroxyl, amino, amido, ether,carbonyl, carboxyl, and combinations thereof; a substituted orun-substituted aryl groups, specifically phenyl groups, wherein thesubstituents are selected from halogen, hydroxyl, alkoxy, alkylcarbonyl,carboxy, and linear or branched or cyclic alkyl groups which may befurther substituted with halogen, hydroxyl, alkoxy, alkylcarbonyl, andcarboxyl groups, and combinations thereof; and a, b, c, x, y and z areindependently between 0 and 100, between 0 and 50, between 0 and 20,between 0 and 10, or between 0 and 5; and n is the number of siloxanerepeating units and is from 10 to 500; 10 to 200; 10 to 100; 10 to 50;10 to 20.

Examples of multifunctional hydroxyl containing silicones includeα-(2-hydroxy-1-methacryloxypropyloxypropyl)-w-butyl-decamethylpentasiloxaneand the difunctional polysiloxanes of Formulae LX or LXI:

wherein R¹ is independently a hydrogen atom or methyl group; R¹⁶ and R¹⁷are independently a linear, branched, or cyclic alkyl group containingone to eight carbon atoms, any of which may be further substituted withat least one hydroxy group, amido, ether, amino, carboxyl, carbonylgroups and combinations thereof; or are independently selected fromunsubstituted C₁₋₄ alkyl groups and C₁₋₄ alkyl groups substituted withhydroxyl or ether; or are selected from methyl, ethyl or—(CH₂CH₂O)_(m)OCH₃; n¹ and n² are independently selected from is 4 to100; 4 to 50; or 4 to 25 and n³ is 1-50, 1-20, and 1-10; m=1-50, 1-20,and 1-10.

At least one silicone-containing component is present in the reactivemixture in an amount sufficient to provide the desired modulus andoxygen permeability of the silicone hydrogel. It has been found that theN-alkyl methacrylamides provide a surprising increase in modulus whenincluded in formulations also comprising a silicone-containingcomponent. This increase in modulus is not observed in conventionalhydrogel formulations. The silicone-containing component may be includedin the reactive mixture in amounts from about 20 to about 60 weight %,or from about 30 to about 55 weight %, from about 30 weight % to about50 weight %, from about 50 weight % to about 60 weight %, all based uponthe total weight of all of the reactive components.

It may also be desirable for the resulting silicone hydrogel to exhibitoxygen permeability greater than about 50 barrers, between about 50barrers and about 200 barrers; between about 70 barrers and about 150barrers; or between about 80 barrers and about 150 barrers.Cross-Linking Agent

The silicone hydrogels of the present invention include at least onecross-linking agent. A variety of cross-linking agents may be used,including silicone-containing and non-silicone containing cross-linkingagents, and mixtures thereof. Non-silicone-containing cross-linkingagents include ethylene glycol dimethacrylate (EGDMA), diethyleneglycoldimethacrylate, trimethylolpropane trimethacrylate (TMPTMA),tetraethylene glycol dimethacrylate (TEGDMA), triallyl cyanurate (TAC),glycerol trimethacrylate, 1,3-propanediol dimethacrylate;2,3-propanediol dimethacrylate; 1,6-hexanediol dimethacrylate;1,4-butanediol dimethacrylate, methacryloxyethyl vinylcarbonate(HEMAVc), allylmethacrylate, methylene bisacrylamide (MBA), polyethyleneglycol dimethacrylate (wherein the polyethylene glycol preferably has amolecular weight up to 5,000 Daltons). Any of the above disclosedmultifunctional silicone-containing components may be used ascross-linking agents.

Other cross-linking agents will be known to one skilled in the art andmay be used to make the silicone hydrogel of the present invention.

The non-silicone containing crosslinking agents are used in amounts fromabout 0.5 weight % to about 20 weight %, 3 weight % to 20 weight % orfrom about 3 weight % to about 15 weight %, all based upon the totalweight of all of the reactive components. The exact amounts varydepending on the mechanical property targets and the other reactivecomponents in the reactive mixture. In other units, the cross-linkingagent may vary from about 16 mmoles in 100 grams of reactive mixture toabout 30 mmoles in 100 grams of reactive mixture, and preferably between16 mmoles/100 grams and 25 mmoles/100 grams of reactive mixture. It maybe desirable to select the crosslinking agents which have reactivegroups with similar reactivity rates with those of the other componentsto form the silicone hydrogel networks. Thus it may be desirable toselect crosslinking agents with at least one reactive group which is thesame as the reactive groups included in the other reactive components.The structure and morphology of the resulting silicone hydrogel may alsobe influenced by the diluent(s) and cure conditions used.

Multifunctional silicone-containing components, including macromers mayalso be included to further increase the modulus and retain tensilestrength. The silicone containing crosslinking agents may be used aloneor in combination with other cross-linking agents. An example of asilicone containing monomer which can act as a crosslinking agent and,when present, does not require the addition of a crosslinking monomer tothe reaction mixture includes α, ω-bismethacryloypropylpolydimethylsiloxane.

When silicone cross-linking agents are used in the formulation, limitingthe number of siloxane repeating units in the silicone cross-linkingagent between 5 and 200, 5 and 150, 5 and 120 allows the retention ofmodulus values in excess of 15,000 psi, without significantly impactingother properties such as oxygen permeability, and elongation. Whenmoduli over 15,000 psi are desired, silicone cross-linking agents may beincluded in amounts between 0 to about 25 weight percent, or betweenabout 10 weight percent and 20 weight percent, all based upon the totalweight of all of the reactive components.

Non-limiting examples of silicone cross-linking agents are shown inFormulae XXVIII, XXIX, and XXXII through XXXVII, and the followingchemical Formulae LXII through LXXII, wherein n is between 1 and 200,preferably n is between 50 and 150, more preferably between 50 and 100,and most preferably n is between 10 and 50.

The aforementioned silicone cross-linking agents may also have acrylate,methacrylate, O-vinylcarbonate, or methacylamide reactive groups. Thesereactive groups may be replaced with any other reactive group capable ofundergoing free radical polymerization, such as, styrenes, vinyl ethers,N-vinyllactams, N-vinylamides, N-vinylimides, N-vinylureas,O-vinylcarbamates, and other vinyl compounds. In some embodiments,silicone cross-linking agents with styryl reactive groups are preferred.

Cross-linking agents that have rigid chemical structures and reactivegroups that undergo free radical polymerization may also be used.Non-limiting examples of suitable rigid structures include cross-linkingagents comprising phenyl and benzyl ring, such are 1,4-phenylenediacrylate, 1,4-phenylene dimethacrylate,2,2-bis(4-methacryloxyphenyl)-propane,2,2-bis[4-(2-acryloxyethoxy)phenyl]propane,2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane, and4-vinylbenzyl methacrylate, and combinations thereof. Rigid crosslinkingagents may be included in amounts between about 2 and about 15, or 2-10,3-7 based upon the total weight of all of the reactive components.

The more NMMA used, the more crosslinker can be used, while stillreaching target water contents, and modulus.

The physical and mechanical properties of the silicone hydrogels of thepresent invention may be optimized for a particular use by adjusting thecomponents in the reactive mixture. It is a benefit of the presentinvention that the desired moduli may be achieved using monofunctionalsilicone-containing components.

Hydrophilic Monomer

The silicone hydrogels of the present invention may further include oneor more hydrophilic monomer. Hydrophilic monomers can be any of thehydrophilic monomers known to be useful to make hydrogels. Classes ofsuitable hydrophilic monomers include acrylic-containing monomers andvinyl-containing monomers. Examples of suitable families of hydrophilicmonomers include N-vinyl amides, N-vinylimides, N-vinyl lactams,hydrophilic (meth)acrylates, (meth)acrylamides, hydrophilic styrenes,vinyl ethers, O-vinyl carbonates, O-vinyl carbamates, N-vinyl ureas,other hydrophilic vinyl compounds and mixtures thereof.

The hydrophilic monomers that may be used to make the polymers of thisinvention have at least one polymerizable double bond and at least onehydrophilic functional group. Such hydrophilic monomers may themselvesbe used as crosslinking agents, however, where hydrophilic monomershaving more than one polymerizable functional group are used, theirconcentration should be limited as discussed above to provide a contactlens having the desired modulus. The term “vinyl-type” or“vinyl-containing” monomers refer to monomers containing the vinylgrouping (—CH═CH₂) and are generally highly reactive. Such hydrophilicvinyl-containing monomers are known to polymerize relatively easily.

“Acrylic-type” or “acrylic-containing” monomers are those monomerscontaining an acrylic group (CH₂═CRCOX) wherein R is H or CH₃, and X isO or N, which are also known to polymerize readily, such as N,N-dimethylacrylamide (DMA), 2-hydroxyethyl methacrylamide, polyethyleneglycolmonomethacrylate, methacrylic acid, acrylic acid, mixtures thereof andthe like.

Hydrophilic monomers with at least one hydroxyl group (hydroxylalkylmonomer) may be used. The hydroxyl alkyl group may be selected fromC₂-C₄ mono or dihydroxy substituted alkyl, and poly(ethylene glycol)having 1-10 repeating units; or is selected from 2-hydroxyethyl,2,3-dihydroxypropyl, or 2-hydroxypropyl, and combinations thereof.

Examples of hydroxyalkyl monomers include 2-hydroxyethyl (meth)acrylate(HEMA), 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,2,3-dihydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate,3-hydroxybutyl (meth)acrylate, 1-hydroxypropyl 2-(meth)acrylate,2-hydroxy-2-methyl-propyl (meth)acrylate, 3-hydroxy-2,2-dimethyl-propyl(meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl(meth)acrylamide, N-(2-hydroxypropyl) (meth)acrylamide,N,N-bis(2-hydroxyethyl) (meth)acrylamide, N,N-bis(2-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl) (meth)acrylamide,2,3-dihydroxypropyl (meth)acrylamide, glycerol (meth)acrylate,polyethyleneglycol monomethacrylate, and mixtures thereof.

The hydroxyalkyl monomer may also be selected from the group consistingof 2-hydroxyethyl methacrylate, glycerol methacrylate, 2-hydroxypropylmethacrylate, hydroxybutyl methacrylate, 3-hydroxy-2,2-dimethyl-propylmethacrylate, and mixtures thereof.

The hydroxyalkyl monomer may comprise 2-hydroxyethyl methacrylate,3-hydroxy-2,2-dimethyl-propyl methacrylate, hydroxybutyl methacrylate orglycerol methacrylate.

When hydrophilic polymers in quantities great than about 3 wt % aredesired, Hydroxyl containing (meth)acrylamides are generally toohydrophilic to be included as compatibilizing hydroxyalkyl monomers, andhydroxyl containing (meth)acrylates may be included in the reactivemixture and the lower amount of hydroxyalkyl monomers may be selected toprovide a haze value to the final lens of less than about 50% or lessthan about 30%.It will be appreciated that the amount of hydroxyl component will varydepending upon a number of factors, including, the number of hydroxylgroups on the hydroxyalkyl monomer, the amount, molecular weight andpresence of hydrophilic functionality on the silicone containingcomponents. The hydrophilic hydroxyl component may be present in thereactive mixture in amounts up to about 15%, up to about 10 wt %,between about 3 and about 15 wt % or about 5 and about 15 wt %.

Hydrophilic vinyl-containing monomers which may be incorporated into thehydrogels include monomers such as hydrophilic N-vinyl lactam andN-vinyl amide monomers including: N-vinyl pyrrolidone (NVP),N-vinyl-2-piperidone, N-vinyl-2-caprolactam,N-vinyl-3-methyl-2-caprolactam, N-vinyl-3-methyl-2-piperidone,N-vinyl-4-methyl-2-piperidone, N-vinyl-4-methyl-2-caprolactam,N-vinyl-3-ethyl-2-pyrrolidone, N-vinyl-4,5-dimethyl-2-pyrrolidone,N-vinyl acetamide (NVA), N-vinyl-N-methylacetamide (VMA),N-vinyl-N-ethyl acetamide, N-vinyl-N-ethyl formamide, N-vinyl formamide,N-vinyl-N-methylpropionamide, N-vinyl-N-methyl-2-methylpropionamide,N-vinyl-2-methylpropionamide, N-vinyl-N,N′-dimethylurea,1-methyl-3-methylene-2-pyrrolidone, 1-methyl-5-methylene-2-pyrrolidone,5-methyl-3-methylene-2-pyrrolidone; 1-ethyl-5-methylene-2-pyrrolidone,N-methyl-3-methylene-2-pyrrolidone, 5-ethyl-3-methylene-2-pyrrolidone,1-N-propyl-3-methylene-2-pyrrolidone,1-N-propyl-5-methylene-2-pyrrolidone,1-isopropyl-3-methylene-2-pyrrolidone,1-isopropyl-5-methylene-2-pyrrolidone, N-vinyl-N-ethyl acetamide,N-vinyl-N-ethyl formamide, N-vinyl formamide, N-vinyl isopropylamide,N-vinyl caprolactam, N-carboxyvinyl-β-alanine (VINAL),N-carboxyvinyl-α-alanine, N-vinylimidazole, and mixtures thereof.

Hydrophilic O-vinyl carbamates and O-vinyl carbonates monomersincluding: N-2-hydroxyethyl vinyl carbamate and N-carboxy-β-alanineN-vinyl ester. Further examples of the hydrophilic vinyl carbonate orvinyl carbamate monomers are disclosed in U.S. Pat. No. 5,070,215, andthe hydrophilic oxazolone monomers are disclosed in U.S. Pat. No.4,910,277. Vinyl carbamates and carbonates, including N-2-hydroxyethylvinyl carbamate, N-carboxy-β-alanine N-vinyl ester, other hydrophilicvinyl monomers, including vinylimidazole, ethylene glycol vinyl ether(EGVE), di(ethylene glycol) vinyl ether (DEGVE), allyl alcohol, 2-ethyloxazoline, vinyl acetate, acrylonitrile, and mixtures thereof.

(Meth)acrylamide monomers may also be included as hydrophilic monomers.Examples include N—N-dimethylacrylamide, acrylamide,N,N-bis(2-hydroxyethyl)acrylamide, acrylonitrile, N-isopropylacrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and any of thehydroxyl functional (meth)acrylamides listed above.

The hydrophilic monomers which may be incorporated into the polymersdisclosed herein may be selected from N,N-dimethyl acrylamide (DMA),2-hydroxyethyl acrylamide, 2-hydroxyethyl methacrylamide,N-hydroxypropyl methacrylamide, bishydroxyethyl acrylamide,2,3-dihydroxypropyl (meth)acrylamide, N-vinylpyrrolidone (NVP),N-vinyl-N-methyl acetamide, N-vinyl methacetamide (VMA), andpolyethyleneglycol monomethacrylate. The hydrophilic monomers may beselected from DMA, NVP, VMA, NVA, and mixtures thereof.

The hydrophilic monomers of the present invention may be macromers oflinear or branched poly(ethylene glycol), poly(propylene glycol), orstatistically random or block copolymers of ethylene oxide and propyleneoxide. The macromer of these polyethers has one reactive group.Non-limiting examples of such reactive groups are acrylates,methacrylates, styrenes, vinyl ethers, acrylamides, methacrylamides, andother vinyl compounds. In one embodiment, the macromer of thesepolyethers comprises acrylates, methacrylates, acrylamides,methacrylamides, and mixtures thereof. Other suitable hydrophilicmonomers will be apparent to one skilled in the art.

The hydrophilic monomers may also comprise charged monomers includingbut not limited to acrylic acid, methacrylic acid, 3-acrylamidopropionicacid (ACA1), 4-acrylamidobutanoic acid, 5-acrylamidopentanoic acid(ACA2), 3-acrylamido-3-methylbutanoic acid (AMBA),N-vinyloxycarbonyl-α-alanine, N-vinyloxycarbonyl-β-alanine (VINAL),combinations thereof and the like.

The hydrophilic monomers may be selected from N, N-dimethyl acrylamide(DMA), N-vinylpyrrolidone (NVP), 2-hydroxyethyl methacrylate (HEMA),N-vinyl methacetamide (VMA), and N-vinyl N-methyl acetamide (NVA),N-hydroxypropyl methacrylamide, mono-glycerol methacrylate,2-hydroxyethyl acrylamide, 2-hydroxyethyl methacrylamide,bishydroxyethyl acrylamide, 2,3-dihydroxypropyl (meth)acrylamide andmixtures thereof.

The hydrophilic monomers may be selected from DMA, NVP, HEMA, VMA, NVA,and mixtures thereof.

The hydrophilic monomer(s) (including the hydroxyl alkyl monomers) maybe present in amounts up to about 60 wt %, between about 1 to about 60weight %, between about 5 to about 50 weight %, or about 5 to about 40weight %, based upon the weight of all reactive components. The siliconehydrogels of the present invention may further comprise at least onewetting agent. As used herein, wetting agents are hydrophilic polymershaving a weight average molecular weight greater than about 5,000Daltons, between about 150,000 Daltons to about 2,000,000 Daltons;between about 300,000 Daltons to about 1,800,000 Daltons; or betweenabout 500,000 Daltons to about 1,500,000 Daltons.

The amount of wetting agent added to the reactive mixtures of thepresent invention may be varied depending on the other components usedand the desired properties of the resulting silicone hydrogel. Whenpresent, the internal wetting agents in reactive mixtures may beincluded in amounts from about 1 weight percent to about 20 weightpercent; from about 2 weight percent to about 15 percent, or from about2 to about 12 percent, all based upon the total weight of all of thereactive components.

Wetting agents include but are not limited to homopolymers,statistically random copolymers, diblock copolymers, triblockcopolymers, segmented block copolymers, graft copolymers, and mixturesthereof. Non-limiting examples of internal wetting agents arepolyamides, polyesters, polylactones, polyimides, polylactams,polyethers, polyacids homopolymers and copolymers prepared by the freeradical polymerization of suitable monomers including acrylates,methacrylates, styrenes, vinyl ethers, acrylamides, methacrylamides,N-vinyllactams, N-vinylamides, O-vinylcarbamates, O-vinylcarbonates, andother vinyl compounds. The wetting agents may be made from anyhydrophilic monomer, including those listed herein.

The wetting agents may include acyclic polyamides comprise pendantacyclic amide groups and are capable of association with hydroxylgroups. Cyclic polyamides comprise cyclic amide groups and are capableof association with hydroxyl groups. Examples of suitable acyclicpolyamides include polymers and copolymers comprising repeating units ofFormula LXXIII or Formula LXXIV:

wherein X is a direct bond, —(CO)—, or —(CO)—NHR^(e)—, wherein R^(e) isa C₁ to C₃ alkyl group; R^(a) is selected from H, straight or branched,substituted or unsubstituted C₁ to C₄ alkyl groups; R^(b) is selectedfrom H, straight or branched, substituted or unsubstituted C₁ to C₄alkyl groups, amino groups having up to two carbon atoms, amide groupshaving up to four carbon atoms, and alkoxy groups having up to twocarbon groups; R^(c) is selected from H, straight or branched,substituted or unsubstituted C₁ to C₄ alkyl groups, or methyl, ethoxy,hydroxyethyl, and hydroxymethyl; R^(d) is selected from H, straight orbranched, substituted or unsubstituted C₁ to C₄ alkyl groups; or methyl,ethoxy, hydroxyethyl, and hydroxymethyl wherein the number of carbonatoms in R^(a) and R^(b) taken together is 8 or less, including 7, 6, 5,4, 3, or less, and wherein the number of carbon atoms in R^(c) and R^(d)taken together is 8 or less, including 7, 6, 5, 4, 3, or less. Thenumber of carbon atoms in R^(a) and R^(b) taken together may be 6 orless or 4 or less. The number of carbon atoms in R^(c) and R^(d) takentogether may be 6 or less. As used herein substituted alkyl groupsinclude alkyl groups substituted with an amine, amide, ether, hydroxyl,carbonyl, carboxy groups or combinations thereof.

R^(a) and R^(b) can be independently selected from H, substituted orunsubstituted C₁ to C₂ alkyl groups. X may be a direct bond, and R^(a)and R^(b) may be independently selected from H, substituted orunsubstituted C₁ to C₂ alkyl groups.

R^(c) and R^(d) can be independently selected from H, substituted orunsubstituted C₁ to C₂ alkyl groups, methyl, ethoxy, hydroxyethyl, andhydroxymethyl.

The acyclic polyamides of the present invention may comprise a majorityof the repeating unit of Formula LXXIII or Formula LXXIV, or the acyclicpolyamides can comprise at least about 50 mole % of the repeating unitof Formula LXXIII or Formula LXXIV, including at least about 70 mole andat least 80 mole %.

Specific examples of repeating units of Formula. LXXIII or Formula LXXIVinclude repeating units derived from N-vinyl-N-methylacetamide,N-vinylacetamide, N-vinyl-N-ethylpropionamide,N-vinyl-N-methyl-2-methylpropionamide, N-vinyl-2-methylpropionamide,N-vinyl-N,N′-dimethylurea, IV N-dimethylacrylamide, methacrylamide andacyclic amides of structures Formula LXXV or Formula LXXVI:

Examples of suitable cyclic amides that can be used to form the cyclicpolyamides of include α-lactam, β-lactam, γ-lactam, δ-lactam, andε-lactam. Examples of suitable cyclic polyamides include polymers andcopolymers comprising repeating units of Formula LXXVII:

wherein f is a number from 1 to 10, X is a direct bond, —(CO)—, or—(CO)—NH—R^(e)—, wherein R^(c) is a C₁ to C₃ alkyl group. In FormulaLXXVII, foray be 8 or less, including 7, 6, 5, 4, 3, 2, or 1. InFormula. LXXVII, f may be 6 or less, including 5, 4, 3, 2, or 1, or maybe from 2 to 8, including 2, 3, 4, 5, 6, 7, or 8, or may be 2 or 3.

When X is a direct bond, f may be 2. In such instances, the cyclicpolyamide may be polyvinylpyrrolidone (PVP).

The cyclic polyamides of the present invention may comprise 50 mole % ormore of the repeating unit of Formula E, or the cyclic polyamides cancomprise at least about 50 mole % of the repeating unit of Formula E,including at least about 70 mole %, and at least about 80 mole %.

Specific examples of repeating units of Formula LXXVII include repeatingunits derived from N-vinylpyrrolidone, which forms PVP homopolymers andvinylpyrrolidone copolymers or N-vinylpyrrolidone substituted withhydrophilic substituents such as phosphoryl choline.

The polyamides may also be copolymers comprising cyclic amide, acyclicamide repeating units or copolymers comprising both cyclic and acyclicamide repeating units. Additional repeating units may be formed frommonomers selected from hydroxyalkyl(meth)acrylates, alkyl(meth)acrylatesor other hydrophilic monomers and siloxane substituted acrylates ormethacrylates. Any of the monomers listed as suitable hydrophilicmonomers may be used as comonomers to form the additional repeatingunits. Specific examples of additional monomers which may be used toform polyamides include 2-hydroxyethylmethacrylate, vinyl acetate,acrylonitrile, hydroxypropyl methacrylate, 2-hydroxyethyl acrylate,methyl methacrylate and hydroxybutyl methacrylate, GMMA, PEGS, and thelike and mixtures thereof. Ionic monomers may also be included. Examplesof ionic monomers include acrylic acid, methacrylic acid,2-methacryloyloxyethyl phosphorylcholine, 3-(dimethyl(4-vinylbenzyl)ammonio)propane-1-sulfonate (DMVBAPS),3-((3-acrylamidopropyl)dimethyl ammonio)propane-1-sulfonate (AMPDAPS),3-((3-methacrylamidopropyl)dimethyl ammonio)propane-1-sulfonate(MAMPDAPS), 3-((3-(acryloyloxy)propyl)dimethylammonio)propane-1-sulfonate (APDAPS),methacryloyloxy)propyl)dimethylammonio)propane-1-sulfonate (MAPDAPS).

The reactive monomer mixture may comprise both an acyclic polyamide anda cyclic polyamide or copolymers thereof. The acyclic polyamide can beany of those acyclic polyamides described herein or copolymers thereof,and the cyclic polyamide can be any of those cyclic polyamides describedherein or copolymers thereof. The polyamide may be selected from thegroup polyvinylpyrrolidone (PVP), polyvinyimethyacetamide (PUMA),polydimethylacryIamide (PDMA), polyvinylacetamide (PNVA),poly(hydroxyethyl(meth)acrylamide), polyacrylamide, and copolymers andmixtures thereof.

The wetting agents may be made from DMA, NVP, HEMA, VMA, NVA, andcombinations thereof. The wetting agents may also be reactivecomponents, as defined herein, by having reactive groups, for example,made by the acylation reaction between pendant hydroxyl groups on HEMArepeating units of an internal wetting agent and methacryloyl chlorideor methacryloyl anhydride. Other methods of functionalization will beapparent to one skilled in the art.

Such internal wetting agents are disclosed in U.S. Pat. Nos. 6,367,929,6,822,016, 7,052,131, 7,666,921, 7,691,916, 7,786,185, 8,022,158, and8,450,387.

The silicone hydrogels of the present invention may include tougheningagents. As previously described, toughening agents are monomers whosecorresponding homo-polymers exhibit glass transition temperatures higherthan 40° C. and when added to the reactive mixture improve theelongation of the resulting silicone hydrogels. Non-limiting examples ofsuch monomers are methyl methacrylate, tert-butyl methacrylate,isobornyl methacrylate, cyclohexyl methacrylate, styrene, substitutedstyrenes, N-4-vinylbenzyl-N-alkyl acetamides, N-4-vinylbenzylpyrrolidone, and combinations thereof.

The reaction mixture may contain additional reactive or non-reactivecomponents such as but not limited to, UV absorbers, visible lightabsorbers, photochromic compounds, pharmaceuticals, nutriceuticals,antimicrobial substances, tints, pigments, copolymerizable andnon-polymerizable dyes, release agents and combinations thereof.

Generally the reactive components are mixed in a diluent to form areaction mixture. Suitable diluents are known in the art. For siliconehydrogels suitable diluents are disclosed in WO 03/022321 and U.S. Pat.No. 6,020,445 the disclosure of which is incorporated herein byreference.Classes of suitable diluents for silicone hydrogel reaction mixturesinclude alcohols having 2 to 20 carbons, amides having 10 to 20 carbonatoms derived from primary amines, and carboxylic acids having 8 to 20carbon atoms. Primary and tertiary alcohols may be used. Preferredclasses include alcohols having 5 to 20 carbons and carboxylic acidshaving 10 to 20 carbon atoms.

Specific diluents which may be used include 1-ethoxy-2-propanol,diisopropylaminoethanol, isopropanol, 3,7-dimethyl-3-octanol, 1-decanol,1-dodecanol, 1-octanol, 1-pentanol, 2-pentanol, 1-hexanol, 2-hexanol,2-octanol, 3-methyl-3-pentanol, tert-amyl alcohol, tert-butanol,2-butanol, 1-butanol, 2-methyl-2-pentanol, 2-propanol, 1-propanol,ethanol, 2-ethyl-1-butanol,(3-acetoxy-2-hydroxypropyloxy)-propylbis(trimethylsiloxy) methylsilane,1-tert-butoxy-2-propanol, 3,3-dimethyl-2-butanol, tert-butoxyethanol,2-octyl-1-dodecanol, decanoic acid, octanoic acid, dodecanoic acid,2-(diisopropylamino)ethanol mixtures thereof and the like.

Preferred diluents include 3,7-dimethyl-3-octanol, 1-dodecanol,1-decanol, 1-octanol, 1-pentanol, 1-hexanol, 2-hexanol, 2-octanol,3-methyl-3-pentanol, 2-pentanol, t-amyl alcohol, tert-butanol,2-butanol, 1-butanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, ethanol,3,3-dimethyl-2-butanol, 2-octyl-1-dodecanol, decanoic acid, octanoicacid, dodecanoic acid, mixtures thereof and the like.

More preferred diluents include 3,7-dimethyl-3-octanol, 1-dodecanol,1-decanol, 1-octanol, 1-pentanol, 1-hexanol, 2-hexanol, 2-octanol,1-dodecanol, 3-methyl-3-pentanol, 1-pentanol, 2-pentanol, t-amylalcohol, tert-butanol, 2-butanol, 1-butanol, 2-methyl-2-pentanol,2-ethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-octyl-1-dodecanol, mixturesthereof and the like.

Aprotic solvents, including amide solvents, hydroxyl substituted, alkylsubstituted on amide portion, including cyclic and acyclic amides,including N-methylpyrrolidone, N-ethylpyrrolidone, N, N-dimethylpropionamide, hydroxyethylpyrrolidone, and the like.

Mixtures of diluents may be used. The diluents may be used in amounts upto about 55% by weight of the total of all components in the reactionmixture. More preferably the diluent is used in amounts less than about45% and more preferably in amounts between about 15 and about 40% byweight of the total of all components in the reaction mixture.

A polymerization initiator is preferably included in the reactionmixture used to form substrates such as contact lenses. Non-limitinginitiators include compounds such as lauryl peroxide, benzoyl peroxide,isopropyl percarbonate, azobisisobutyronitrile, and the like, thatgenerate free radicals at moderately elevated temperatures, andphotoinitiator systems such as aromatic alpha-hydroxy ketones,alkoxyoxybenzoins, acetophenones, acylphosphine oxides, bisacylphosphineoxides, and diketones with tertiary amines, mixtures thereof, and thelike.

Illustrative examples of photoinitiators are 1-hydroxycyclohexyl phenylketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one,bis(2,6-dimethoxybenzoyl)-2,4-4-trimethylpentyl phosphine oxide(DMBAPO), bis(2,4,6-trimethylbenzoyl)-phenyl phosphineoxide (Irgacure819), 2,4,6-trimethylbenzyldiphenyl phosphine oxide and2,4,6-trimethylbenzoyl diphenylphosphine oxide, benzoin methyl ester anda combination of camphorquinone and ethyl 4-(N,N-dimethylamino)benzoate.Commercially available visible light initiator systems include Irgacure819, Irgacure 1700, Irgacure 1800, Irgacure 819, Irgacure 1850 (all fromCiba Specialty Chemicals) and Lucirin TPO initiator (available fromBASF). Commercially available UV photoinitiators include Darocur 1173and Darocur 2959 (Ciba Specialty Chemicals). These and otherphotoinitiators which may be used are disclosed in Volume III,Photoinitiators for Free Radical Cationic & Anionic Photopolymerization,2nd Edition by J. V. Crivello & K. Dietliker; edited by G. Bradley; JohnWiley and Sons; New York; 1998, which is incorporated herein byreference.

The initiator is used in the reaction mixture in effective amounts toinitiate polymerization of the reaction mixture typically in amountsfrom about 0.1 to about 2 weight percent of the reactive mixture.Polymerization of the reaction mixture can be initiated using theappropriate choice of heat, visible light, ultraviolet irradiation, orother means depending on the polymerization initiator used.Alternatively, initiation can be conducted without a photoinitiatorusing e-beam, for example. However, when a photoinitiator is used, thepreferred initiators are bisacylphosphine oxides, such asbis(2,4,6-trimethylbenzoyl)-phenyl phosphine oxide (Irgacure 819®) or acombination of 1-hydroxycyclohexyl phenyl ketone andbis(2,6-dimethoxybenzoyl)-2,4-4-trimethylpentyl phosphine oxide(DMBAPO), and the preferred method is visible light irradiation. Themost preferred photoinitiator is bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819®).

The reaction mixtures can be formed by any of the methods known to thoseskilled in the art, such as shaking or stirring, and then used to formpolymeric articles or devices by known methods. For example, biomedicaldevices may be prepared by mixing reactive components and the diluentswith a polymerization initiator and curing by appropriate conditions toform a product that can be subsequently formed into the appropriateshape by lathing, cutting and the like. Alternatively, the reactionmixture may be placed in a mold and subsequently cured into theappropriate article.

Various processes are known for processing the reaction mixture in theproduction of contact lenses, including spin casting and static casting.Spin casting methods are disclosed in U.S. Pat. Nos. 3,408,429 and3,660,545; and static casting methods are disclosed in U.S. Pat. No.4,113,224 and U.S. Pat. No. 4,197,266. The preferred method forproducing contact lenses is by the molding of the silicone hydrogels,which is economical and enables precise control over the final shape ofthe hydrated lens. For this method, the reaction mixture is placed in amold having the shape of the final desired silicone hydrogel contactlens, and the reaction mixture is subjected to conditions whereby themonomers polymerize. Subsequently, the molded lens is treated withsolvents to remove the diluent and ultimately replace it with water orpackaging solution, thereby producing a hydrated silicone hydrogelcontact lens. Some diluents may be removed by heat, vacuum orevaporation. In these cases lenses may be mechanically demolded withoutsolvent. This method can be used to form contact lenses and is furtherdescribed in U.S. Pat. Nos. 4,495,313, 4,680,336, 4,889,664 and5,039,459 which are herein incorporated by reference.

Biomedical devices, and particularly ophthalmic lenses, have a balanceof properties which makes them particularly useful. These properties maybe physical, mechanical, or biological in nature. Non-limiting physicalproperties of a contact lens include haze, water content, oxygenpermeability, and contact angle. Non-limiting mechanical properties of acontact lens include Young's modulus, tensile strength, elongation tobreak, and toughness.

All combinations of the above ranges are deemed to be within the presentinvention.

For patients with astigmatism, soft contact lenses must be rotationallystabilized in order for the optical correction to be effective. Suchstabilization is usually accomplished by the use of stabilization zoneson the posterior side of the contact lens that limit rotation.Alternatively, an astigmatic masking lens may be worn in which the lensvaults over the cornea thereby creating a space between the cornealsurface and the lens. That space effectively masks the astigmaticproperties of the cornea. In order for a soft contact lens to vault overthe cornea surface, the central portion of the lens must be stiff enoughto maintain the shape required for vaulting without causing patientdiscomfort at the same time. The present invention is directed tosilicone hydrogels that have sufficient stiffness for vaulting atrelatively high water contents to form composite soft contact lenseswith other silicone hydrogels that are comfortable to wear.

The silicone hydrogels of the present invention may be used to form theunitary contact lenses, or the central region of a composite contactlenses having a central region and a peripheral region. The centralregion is formed from a silicone hydrogel formed from reactive mixturescomprising at least one N-alkyl methacrylamide, at least one hydrophilicmonomer, at least one silicon-containing component, and at least onecross-linking agent, with water contents from about 10 weight percent toabout 40 weight percent and moduli from about 15,000 psi to about200,000 psi and the peripheral region is formed from compositionallydistinct silicone hydrogels having water contents of about 10 to about40 weight percent and moduli from about 20 to about 500 psi.

In another embodiment, a process for making such composite contactlenses is described comprising (a) dosing a first silicone hydrogelformulation of claim 1 into a first mold, (b) partially curing the firstsilicone hydrogel formulation into a gel, (c) dosing a second siliconehydrogel formulation into the first mold, (d) allowing time for thesecond silicone hydrogel formulation to imbibe into the gel, (e) placinga second mold on top of the first mold, and (f) fully curing thecombination to form the composite contact lens.

The central circular area may be the same size as the optic zone, whichin a typical contact lens is about 9 mm or less in diameter. In oneembodiment, the central circular area has a diameter of between about 4and about 7 mm and in another between about 4 and about 6 mm indiameter.

Optionally, the first monomer mixture may be at least partiallypolymerized through a controlled curing mechanism. Then, a dose of asecond monomer mixture, which will form a hydrogel having a modulus ofless than about 200 psi, or less than about 150 psi, is dosed on the topof the first monomer mixture. The dose of the second monomer mixturefills the concave front curve to the desired amount and then the basecurve is provided and the mold halves are put into their final curingposition and the monomer mixtures are cured and/or polymerizedcompleting the molding process. Where the polymerization processincludes a photopolymerization mechanism, the radiation, may be directedto either the front curve mold half or the base curve mold half, orboth. The molded lens is then extracted to remove the un-desiredchemical components and hydrated.

In an alternative method, the first monomer mixture is provided in thecenter of a front curve mold and then an annular ring of the secondmonomer mixture is dosed at the edge of the front curve mold. Theresultant annular ring of the second reactive mixture is drawn to thecenter of the front curve by gravity. The base curve mold is thensupplied and the curing is initiated and completed and extraction andhydration step(s) proceed to form the final hydrogel contact lensproduct.

It is desirable to prevent substantial mixing of the first and secondmonomer mixtures to preserve the desired moduli values in the centraland peripheral zones. Increasing the viscosity of the first monomermixture as compared to the second, peripheral monomer mixture, canreduce molecular diffusion of the monomers when a cure (either partialor full) of the first monomer mixture in the central zone is notutilized. Using a first monomer mixture that has higher viscosity thanthe clear monomer mixture helps to reduce the shear at the interface ofthe two monomers mixtures thereby reducing the physical mixing. Ananalysis of the Stokes-Einstein equation, shown below, illustrates theparameters that affect the diffusivity of a material:

$D = \frac{kT}{6{\pi\mu}\; r}$where D is the molecular diffusivity, k the Boltzmann constant, T thetemperature, μ the viscosity and r the radius of the molecule. Operatingat lower temperatures and using monomers of higher viscosities tends toreduce the molecular diffusion rate. In one embodiment the viscosity ofthe first monomer mixture is at least about 1000 cp higher than theviscosity of the peripheral monomer mixture and in another embodiment atleast about 1500 cp higher.

However, controlling the viscosity of the monomer mixtures as disclosedin US2003/0142267 was insufficient to provide hydrogel contact lenseshaving suitable optics and comfort. It has been found that employing apartial or complete cure of the first monomer mixture and balancing theexpansion factor of the polymers formed from the first and secondmonomer mixture hydrogel contact lenses having desirable optics andcomfort may be produced. In one embodiment the expansion factors of thepolymers formed from the respective monomer mixtures are within about10% in some embodiments within about 8% and in other embodiments withinabout 5%. The expansion factor may be adjusted by manipulating a numberof formulation variables including the diluent concentration, theconcentration and hydrophilicity or hydrophobicity of hydrophilic andhydrophobic components and concentration of initiator and crosslinker,and combinations thereof. It may be desirable to maintain theconcentration of the silicone components and replace a part of one ofhydrophilic components. In these embodiments, multiple adjustments maybe needed to achieve the desired expansion factor.

In addition, other formulation variables may be modified to achieve thedesired expansion factor. For example, varying the concentration of thehydrophilic components, the diluent concentration and the initiatorconcentration, and combinations thereof have been effective at providingphotochromic contact lenses having desirable optics and comfort. In oneembodiment a wetting agent, such as poly(vinyl pyrrolidone) (PVP),methacrylic acid, polydimethylacrylamide or poly(vinyl methacetamide)may be added to the monomer mixtures. The same or similar components maybe used in both the first and second monomer mixtures. For example, itmay be desirable to include the same hydrophilic components in bothmonomer mixtures. In this case, formulation variables in addition to theconcentration of hydrophilic components may be varied.

When a single sided cure is used the expansion factor may be matchedusing monomers, diluent concentration and combinations thereof. Wherecure is effected from only one side (such as during photocuring),increasing the initiator concentration may also be desirable.

Test Methods

Standard deviations are shown in parentheses. It will be appreciatedthat all of the tests specified herein have a certain amount of inherenterror. Accordingly, the results reported herein are not to be taken asabsolute numbers, but numerical ranges based upon the precision of theparticular test.

The water content was measured as follows: lenses to be tested wereallowed to sit in packing solution for 24 hours. Each of three test lenswere removed from packing solution using a sponge tipped swab and placedon blotting wipes which have been dampened with packing solution. Bothsides of the lens were contacted with the wipe. Using tweezers, the testlens were placed in a weighing pan (that was preweighed) and the weightof the wet lenses was obtained. Two more sets of samples were preparedand weighed as above.

The dry weight was measured by placing the sample pans in a vacuum ovenwhich has been preheated to 60° C. for 30 minutes. Vacuum was applieduntil at least 0.4 inches Hg is attained. The vacuum valve and pump wereturned off and the lenses were dried for a minimum of twelve hours. Thepurge valve was opened and the oven was allowed reach atmosphericpressure. The pans were removed and weighed. The water content wascalculated as follows:

Wet  weight = combined  wet  weight  of  pan  and  lenses − weight  of  weighing  panDry  weight = combined  dry  weight  of  pan  and  lens − weight  of  weighing  pan$\mspace{76mu}{{\%\mspace{14mu}{water}\mspace{14mu}{content}} = {\frac{( {{{wet}\mspace{14mu}{weight}} - {{dry}\mspace{14mu}{weight}}} )}{{wet}\mspace{14mu}{weight}} \times 100}}$

The average and standard deviation of the water content are calculatedfor the samples are reported.

Haze was measured by placing a hydrated test lens in borate bufferedsaline in a clear glass cell at ambient temperature above a flat blackbackground, illuminating from below with a fiber optic lamp(Dolan-Jenner PL-900 fiber optic light with 0.5″ diameter light guide)at an angle 66° normal to the lens cell, and capturing an image of thelens from above, normal to the lens cell with a video camera (DVC1300C:19130 RGB camera or equivalent equipped with a suitable zoomcamera lens) placed 14 mm above the lens holder. The background scatteris subtracted from the scatter of the test lens by subtracting an imageof a blank cell with borate buffered saline (baseline) using EPIX XCAP V3.8 software. The value for high end scatter (frosted glass) is obtainedby adjusting the light intensity to be between 900 to 910 meangrayscale. The value of the background scatter (BS) is measured using asaline filled glass cell. The subtracted scattered light image isquantitatively analyzed, by integrating over the central 10 mm of thelens, and then comparing to a frosted glass standard. The lightintensity/power setting was adjusted to achieve a mean grayscale valuein the range of 900-910 for the frosted glass standard; at this setting,the baseline mean grayscale value was in the range of 50-70. The meangrayscale values of the baseline and frosted glass standard are recordedand used to create a scale from zero to 100, respectively. In thegrayscale analysis, the mean and standard deviations of the baseline,frosted glass, and every test lens was recorded. For each lens, a scaledvalue was calculated according to the equation: scaled value equals themean grayscale value (lens minus baseline) divided by the mean grayscalevalue (frosted glass minus baseline) times by 100. Three to five testlenses are analyzed, and the results are averaged.

Water content was measured gravimetrically. Lenses were equilibrated inpacking solution for 24 hours. Each of three test lens are removed frompacking solution using a sponge tipped swab and placed on blotting wipeswhich have been dampened with packing solution. Both sides of the lensare contacted with the wipe. Using tweezers, the test lens are placed ina tared weighing pan and weighed. The two more sets of samples areprepared and weighed. All weight measurements were done in triplicate,and the average of those values used in the calculations. The wet weightis defined as the combined weight of the pan and wet lenses minus theweight of the weighing pan alone.

The dry weight was measured by placing the sample pans in a vacuum ovenwhich has been preheated to 60° C. for 30 minutes. Vacuum was applieduntil the pressure reaches at least 1 inch of Hg is attained; lowerpressures are allowed. The vacuum valve and pump are turned off and thelenses are dried for at least 12 hours; typically overnight. The purgevalve is opened allowing dry air or dry nitrogen gas to enter. The ovenis allowed reach atmospheric pressure. The pans are removed and weighed.The dry weight is defined as the combined weight of the pan and drylenses minus the weight of the weighing pan alone. The water content ofthe test lens was calculated as follows:

${\%\mspace{14mu}{water}\mspace{14mu}{content}} = {\frac{( {{{wet}\mspace{14mu}{weight}} - {{dry}\mspace{14mu}{weight}}} )}{{wet}\mspace{14mu}{weight}} \times 100}$The average and standard deviation of the water content were calculatedand the average value reported as the percent water content of the testlens.

The refractive index (RI) of a contact lens was measured by a LeicaARIAS 500 Abbe refractometer in manual mode or by a Reichert ARIAS 500Abbe refractometer in automatic mode with a prism gap distance of 100microns. The instrument was calibrated using deionized water at 20° C.(+/−0.2° C.). The prism assembly was opened and the test lens placed onthe lower prism between the magnetic dots closest to the light source.If the prism is dry, a few drops of saline were applied to the bottomprism. The front curve of the lens was against the bottom prism. Theprism assembly was then closed. After adjusting the controls so that theshadow line appeared in the reticle field, the refractive index wasmeasured. The RI measurement was made on five test lenses. The averageRI calculated from the five measurements was recorded as the refractiveindex as well as its standard deviation.

Oxygen permeability (Dk) was determined by the polarographic methodgenerally described in ISO 9913-1:1996 and ISO 18369-4:2006, but withthe following modifications. The measurement was conducted at anenvironment containing 2.1% oxygen created by equipping the test chamberwith nitrogen and air inputs set at the appropriate ratio, for example,1800 mL/min of nitrogen and 200 mL/min of air. The t/Dk is calculatedusing the adjusted oxygen concentration. Borate buffered saline wasused. The dark current was measured by using a pure humidified nitrogenenvironment instead of applying MMA lenses. The lenses were not blottedbefore measuring. Four lenses were stacked instead of using lenses ofvarious thickness (t) measured in centimeters. A curved sensor was usedin place of a flat sensor; radius was 7.8 mm. The calculations for a 7.8mm radius sensor and 10% (v/v) air flow are as follows:Dk/t=(measured current−dark current)×(2.97×10⁻⁸ mL O₂/(μA-sec-cm²-mm Hg)The edge correction was related to the Dk of the material.For all Dk values less than 90 barrers:t/Dk(edge corrected)=[1+(5.88×t)]×(t/Dk)For Dk values between 90 and 300 barrers:t/Dk(edge corrected)=[1+(3.56×t)]×(t/Dk)For Dk values greater than 300 barrers:t/Dk(edge corrected)=[1+(3.16×t)]×(t/Dk)

Non-edge corrected Dk was calculated from the reciprocal of the slopeobtained from the linear regression analysis of the data wherein the xvariable was the center thickness in centimeters and the y variable wasthe t/Dk value. On the other hand, edge corrected Dk was calculated fromthe reciprocal of the slope obtained from the linear regression analysisof the data wherein the x variable was the center thickness incentimeters and the y variable was the edge corrected t/Dk value. Theresulting Dk value was reported in barrers.

Wettability of lenses was determined using the methods below. Dynamiccontact angle (DCA) was determined by a Wilhelmy plate method using aCahn DCA-315 instrument at room temperature and using deionized water asthe probe solution. The experiment was performed by dipping the lensspecimen of known parameter into the packing solution of known surfacetension while measuring the force exerted on the sample due to wettingby a sensitive balance. The advancing contact angle of the packingsolution on the lens is determined from the force data collected duringsample dipping. The receding contact angle is likewise determined fromforce data while withdrawing the sample from the liquid. The Wilhelmyplate method is based on the following formula: Fg=γρ cos θ−B, whereinF=the wetting force between the liquid and the lens (mg),g=gravitational acceleration (980.665 cm/sec²), γ=surface tension ofprobe liquid (dyne/cm), ρ=the perimeter of the contact lens at theliquid/lens meniscus (cm), θ=the dynamic contact angle (degree), andB=buoyancy (mg). B is zero at the zero depth of immersion. Four teststrips were cut from the central area of the contact lens. Each stripwas approximately 5 mm in width and equilibrated in packing solution.Then, each sample was cycled four times, and the results were averagedto obtain the advancing and receding contact angles of the lens.

In some Examples, wettability of lenses was determined using a sessiledrop technique measured using KRUSS DSA-100 TM instrument at roomtemperature and using DI water as probe solution. The lenses to betested (3-5/sample) were rinsed in DI water to remove carry over frompacking solution. Each test lens was placed on blotting lint free wipeswhich were dampened with packing solution. Both sides of the lens werecontacted with the wipe to remove surface water without drying the lens.To ensure proper flattening, lenses were placed “bowl side down” on theconvex surface of contact lens plastic molds. The plastic mold and thelens were placed in the sessile drop instrument holder, ensuring propercentral syringe alignment. A 3 to 4 microliter drop of deionized waterwas formed on the syringe tip using DSA 100-Drop Shape Analysis softwareensuring the liquid drop was hanging away from the lens. The drop wasreleased smoothly on the lens surface by moving the needle down. Theneedle was withdrawn away immediately after dispensing the drop. Theliquid drop was allowed to equilibrate on the lens for 5 to 10 seconds,and the contact angle was measured between the drop image and the lenssurface.

The mechanical properties of the contact lenses were measured by using atensile testing machine such as an Instron model 1122 or 5542 equippedwith a load cell and pneumatic grip controls. Minus one diopter lens isthe preferred lens geometry because of its central uniform thicknessprofile. A dog-bone shaped sample cut from a −1.00 power lens having a0.522 inch length, 0.276 inch “ear” width and 0.213 inch “neck” widthwas loaded into the grips and elongated at a constant rate of strain of2 inches per minute until it breaks. The center thickness of thedog-bone sample was measured using an electronic thickness gauge priorto testing. The initial gauge length of the sample (Lo) and samplelength at break (Lf) were measured. At least five specimens of eachcomposition were measured, and the average values were used to calculatethe percent elongation to break: percent elongation=[(Lf−Lo)/Lo]×100.The tensile modulus was calculated as the slope of the initial linearportion of the stress-strain curve; the units of modulus are pounds persquare inch or psi. The tensile strength was calculated from the peakload and the original cross-sectional area: tensile strength=peak loaddivided by the original cross-sectional area; the units of tensilestrength are psi. Toughness was calculated from the energy to break andthe original volume of the sample: toughness=energy to break divided bythe original sample volume; the units of toughness are in-lbs/in³.

Samples cast as flats were also measured by Instron testing; however,the test articles were prepared from flat circular plastic molds(diameter about 15 mm) similar to the molds used to make contact lensesbut without curvature to produce flat round disks. The molds weredesigned to make disks with center thicknesses between 250 and 550microns, depending on the volume of reactive monomer mixture dosed. Thedisks were cut to the desired sample size (width: 3.1 mm; length: about7 mm). The crosshead of a constant rate-of-movement type-testing machinewas equipped with a 100 Newton load cell and pneumatic action grips (250Newton maximum) with diamond serrated jaw faces. The specimen was loadedinto the grips and then elongated at 1 inch per minute until it breaks.The tensile properties are obtained from the resulting stress-straincurve. Additionally, for all mechanical testing experiments, sampleswere stored in packing solution until immediately before the analysis tominimize the effects of dehydration.

Center thickness was measured using an electronic thickness gauge.

OCT Test Method:

A model eye was manufactured from PMMA for the purpose of testingprototype lens designs for corneal masking in vitro. The model eye wasdesigned to have approximately 1.80 diopters of corneal astigmatism,with principal meridian curvatures of 7.688 mm and 8.016 mm for thesteep and flat meridians, respectively. The prototype lens design wasplaced onto the model eye with a saline solution between the lens andeye surface acting as surrogate for tears. A Bioptigen Envisu OpticalCoherence Tomographer (OCT, model R2310) with a 20 mm objective lens wasused to image the prototype lens and model eye system to determine if avolume of saline was visible between the model surface and lens backsurface. As can be seen in the FIGURE below, the OCT image confirmed thepresence of a tear volume between the model eye and lens back surface,indicating the lens successfully vaulted the model corneal surface.

The following abbreviations will be used throughout the Examples

BC: back curve plastic mold

FC: front curve plastic mold

NVP: N-vinylpyrrolidone (Acros Chemical)

DMA: N,N-dimethylacrylamide (Jarchem)

HEMA: 2-hydroxyethyl methacrylate (Bimax)

NMMA: N-methyl methacrylamide

VMA: N-vinyl N-methyl acetamide (Aldrich)

Blue HEMA:1-amino-4-[3-(4-(2-methacryloyloxy-ethoxy)-6-chlorotriazin-2-ylamino)-4-sulfophenylamino]anthraquinone-2-sulfonicacid, as described in Example 4 of U.S. Pat. No. 5,944,853

Styryl-TRIS: tris(trimethylsiloxy)silyl styrene

pVMA: poly(N-vinyl N-methyl acetamide)

PVP: poly(N-vinylpyrrolidone) K90 (ISP Ashland)

EGDMA: ethylene glycol dimethacrylate (Esstech)

TEGDMA: triethylene glycol dimethacrylate (Esstech)

TMPTMA: trimethylolpropane trimethacrylate (Esstech)

BMPP: 2,2-bis(4-methacryloxyphenyl)-propane (PolySciences)

BAPP: 2,2-bis[4-(2-acryloxyethoxy)phenyl]propane (PolySciences)

BHMPP: 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane(PolySciences)

Tegomer V-Si 2250: diacryloxypolydimethylsiloxane, having 20 averagedimethyl siloxy repeating units (Evonik)

D3O: 3,7-dimethyl-3-octanol (Vigon)

Irgacure 819: bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide

Irgacure 1870: blend ofbis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphineoxide and1-hydroxy-cyclohexyl-phenyl-ketone

mPDMS: monomethacryloxypropyl terminated mono-n-butyl terminatedpolydimethylsiloxane, (800-1000 MW) (Gelest)

HO-mPDMS: mono-(2-hydroxy-3-methacryloxypropyl)-propyl ether terminatedmono-n-butyl terminated polydimethylsiloxane (400-1000 MW) (DSM)

SiMAA: 2-propenoic acid,2-methyl-2-hydroxy-3-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]propoxy]propylester (Toray)

SA2:N-(2,3-dihydroxylpropyl)N-(3-tetra(dimethylsiloxy)dimethyIbutylsilane)propyl)acrylamide

TAM: t-amyl alcohol (BASF)

3E3P: 3-ethyl 3-pentanol

DI water: deionized water

IPA: isopropyl alcohol

Norbloc: 2-(2-hydroxy-5-methacrylyloxyethylphenyl)-2H-benzotriazole(Janssen)

PP: polypropylene

Zeonor: polycycloolefin thermoplastic polymer (Nippon Zeon Co Ltd)

Borate Buffer: a solution prepared by dissolving 8.3 gm NaCl (from SigmaAldrich), 9.1 gm boric acid (from Mallinckrodt) and 1 gm sodium borate(from Mallinckrodt) in 1 L deionized water (from Milli Q).

Synthetic Example 1: Preparation of Poly(N-Vinyl N-Methyl Acetamide)(pVMA)

380 mL (3.48 mol) of distilled N-vinyl-N-methyl acetamide and 187 mg(1.14 mmol) of azobisisobutyronitrile were added to a 3-neck roundbottom flask fitted with reflux condenser, magnetic stirring bar andthermocouple and purged of oxygen gas for 2 hours by bubbling nitrogengas through the reaction mixture. Then, the reaction mixture was heatedat 75° C. for 24 hours during which time the reaction mixturesolidified. The reaction product was quenched in air and isolated bywork-up procedure 1 or work-up procedure 2. Work-up Procedure 1: Thereaction product was dissolved in 800 mL of methylene chloride at 40° C.and cooled to room temperature. The solution was poured into 2 L of colddiethyl ether with manual stirring to afford a white solid afterdecanting off the solvents. The solid product was air dried followed byvacuum drying overnight at 50° C. The precipitated product was groundinto a fine white powder and vacuum dried overnight at 50° C. (85%yield). Work-up Procedure 2: The reaction product was dissolved in waterand dialyzed extensively in dialysis membrane tubing (Spectra Pore MWCO3500) and freeze dried (LABCONCO, Freezone® Triad™ freeze dry system,Model #7400030) or spray dried (BUCHI mini spray dryer, Model #B-290).The molecular weight was determined by Size Exclusion Chromatographywith Multi-Angle Light Scattering (SEC-MALS). The SEC-MALS setupemployed methanol (with 10 mM LiBr) as the mobile phase at a flow rateof 0.6 mL/min at 50° C. Three Tosoh Biosciences TSK-gel columns inseries were used [SuperAW30004 um, 6.0 mm ID×15 cm (PEO/DMF ExclusionLimit=60,000 g/mole), SuperAW40006 um, 6.0 mm ID×15 cm (PEO/DMFExclusion Limit=400,000 g/mole) and a SuperAW50007 um, 6.0 mm ID×15 cm(PEO/DMF Exclusion Limit=4,000,000 g/mole)] with an online Agilent 1200UV/VIS diode array detector, a Wyatt Optilab rEX interferometricrefractometer, and a Wyatt miniDAWN Treos multiangle laser scattering(MALS) detector (λ=658 nm). A dη/dc value of 0.1829 mL/g at 30° C.(λ=658 nm) was used for absolute molecular weight determination.Absolute molecular weights and polydispersity data were calculated usingthe Wyatt ASTRA 6.1.1.17 SEC/LS software package. The weight averagemolecular weight typically varied from about 500 KDa to about 700 KDa,and the polydispersity varied from about 1.8 to about 2.8.

Comparative Examples 1-12 and Examples 1-5

Each reactive mixture was formed by mixing the reactive componentslisted in Tables 1 and 2 and then degassed by applying vacuum at ambienttemperature for about 20 minutes. In a glove box with a nitrogen gasatmosphere and less than 0.1 percent oxygen gas, about 100 μL of thereactive mixture was then dosed at room temperature into the FC madefrom Zeonor. The BC, made from 55:45 (w/w) blend ofZeonor:polypropylene, was placed on the front curve mold. The molds wereequilibrated for a minimum of twelve hours in the glove box prior todosing. The tray was transferred into an adjacent glove box maintainedat 50-60° C., and the lenses were cured from the bottom for 20 minutesusing TLO3 fluorescent bulbs having intensity of 4-5 mW/cm².

The lenses were manually de-molded with most lenses adhering to the BCand released using 70-50% IPA, followed by washing two times with 70-25%IPA for about 0.5-2.0 hours, DI water for about one hour, and finallytwo times with borate buffered packaging solution for about 30 minutes.The lenses were sterilized by autoclaving at 122° C. for 30 minutes. Thephysical and mechanical properties of the sterile lenses were measuredand are listed in Table 3.

TABLE 1 Component CE1 CE2 CE3 OH-mPDMS 0 0 0 n = 4 mPDMS 1000 0 0 0 DMA65.25 32.62 0 NMMA 0 32.63 65.25 HEMA 30 30 30 TEGDMA 2.5 2.5 2.5Norbloc 1.75 1.75 1.75 CGI 819 0.5 0.5 0.5 Diluent 20 20 20 TAM 100 100100

TABLE 2 Component Ex.1 CE4 CE5 Ex 2 Ex 3 Ex. 4 Ex. 5 CE6 CE7 CE8 CE9CE10 CE11 CE12 OH-mPDMS 40 40 16.5 16.5 16.5 16.5 16.5 16.5 16.5 16.516.5 16.5 16.5 16.5 n = 4 mPDMS 1000 0 0 27.5 27.5 27.5 27.5 27.5 27.527.5 27.5 27.5 27.5 27.5 27.5 NVP 0 0 46.65 35.15 23.35 11.50 0 44.1541.65 39.15 35.15 23.35 11.5 0 DMA 0 50.5 0 0 0 0 0 2.5 5.0 7.5 11.523.30 35.15 46.65 NMMA 50 0 0 11.5 23.3 35.15 46.65 0 0 0 0 0 0 0 HEMA6.75 6.75 6.75 6.75 6.75 6.75 6.75 6.75 6.75 6.75 6.75 6.75 6.75 6.75EGDMA 1 0.5 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35Norbloc 2 2 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75CGI 819 0.25 0.25 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5Diluent 0 0 10 10 10 10 10 10 10 10 10 10 10 10 TAM 100 100 100 100 100100 100 100 100 100 100 100 100 100

TABLE 3 Example % % Mechanicals # Water Haze DCA Mod. (psi) Elong. (%)D_(k) CE1 81 (1) 2 (0) 67 (4) 39 (7)  63 (30) 47 CE 2 83 (0) 2 (1) 83(8) 16 (3)  93 (45) 49 CE3 79 (0) NT 113 (13) 20 (3)  74 (25) NT Ex. 165 (0) 51 (13)  77 (12) 316 (18) 204 (45) 50 CE4 60 (0) 5 (1) 127 (14)54 (7) 227 (52) 49 CES 61 (0) 6 (1) 48 (6)  75 (10) 145 (57) 92 Ex 2 63(0) 7 (0) 116 (9)  53 (5) 250 (49) 85 Ex 3 60 (0) 7 (0) 112 (7)  103(8)  242 (43) 75 Ex 4 59 (0) 7 (1) 109 (8)  223 (32) 194 (36) 57 Ex 5 60(0) 50 (32) 95 (7) 365 (77) 118 (15) 48 CE6 61 (0) 6 (1) 48 (6)  75 (10)145 (57) 92 CE7 63 (0) 7 (1) 79 (9) 57 (6) 171 (36) 89 CE8 63 (0) 9 (1)107 (3)  52 (4) 164 (53) 89 CE9 63 (0) 9 (1) 110 (4)  46 (6) 162 (45) 89CE10 60 (0) 6 (1) 119 (15) 53 (6) 184 (56) 85 CE11 56 (0) 4 (0) 114 (13)66 (6) 195 (44) 72 CE12 54 (0) 4 (1) 107 (5)   87 (10) 211 (56) 56

The comparative Examples contain no NMMA and have moduli less than about90 psi. Surprisingly, replacing either DMA or NVP with NMMA results indramatically increased modulus values. For example, replacing the NVP inComparative Example 5 with NMMA (46.65%, Ex. 5), increased the modulusfrom 75 psi to 365 psi. Similarly, replacing the DMA from ComparativeExamples 9-12 with NMMA also showed dramatic increases in modulus,particularly in concentrations of about 20% or greater as shown in Table4 below. The increases in modulus values ranged from 10% at 11.5 wt %NMMA to over 300% at 46.65 wt % NMMA. Water content for Examples 2-5remained between 59 and 63%, and clarity was acceptable in Examples 2-5.

Ex# [NMMA] [DMA] Mod (psi) 2 11.5 0 53 (5) 3 23.3 0 103 (8)  4 35.15 0223 (32) 5 46.65 0 365 (77) CE9 0 11.5 46 (6) CE10 0 23.3 53 (6) CE11 035.15 66 (6) CE12 0 46.65  87 (10)

Examples 6-16

Each reactive mixture was formed by mixing the reactive componentslisted in Table 4 and then degassed by applying vacuum at ambienttemperature for about 20 minutes. In a glove box with a nitrogen gasatmosphere and less than 0.1 percent oxygen gas, about 100 μL of thereactive mixture was then dosed at room temperature into the FC madefrom a 90:10 (w/w) blend of Zeonor:polypropylene. The BC made frompolypropylene was then placed on the front curve mold. A quartz platewas placed on top of a tray of eight such mold assemblies to maintainproper fitting. The molds were equilibrated for a minimum of twelvehours in the glove box prior to dosing. The tray was transferred into anadjacent glove box maintained at 60-65° C., and the lenses were curedfrom the top for 12 minutes using TLO3 fluorescent bulbs havingintensity of 4-5 mW/cm².

The lenses were manually de-molded with most lenses adhering to the BCand released using 70-50% IPA, followed by washing two times with 70-25%IPA for about 0.5-2.0 hours, DI water for about one hour, and finallytwo times with borate buffered packaging solution for about 30 minutes.The lenses were sterilized by autoclaving at 122° C. for 30 minutes. Thephysical and mechanical properties of the sterile lenses were measuredand are listed in Table 5.

TABLE 4 Ex Ex Ex CEx Ex Ex Ex Ex Component Ex 6 Ex 7 Ex 8 Ex 9 10 11 1213 13 14 15 16 OH-mPDMS 60 60 55 52.5 50 47.5 45 45 42.5 21.75 17.5 12.5n = 4 OH-mPDMS 0 0 0 0 0 0 0 0 0 21.25 25 30 n = 15 NMMA 7.5 7.5 7.5 7.57.5 10 12.5 0 15 15 15 15 DMA 0 0 0 0 0 0 0 12.5 0 0 0 0 HEMA 15 16.9816.98 16.98 16.98 16.98 16.98 16.98 16.98 16.98 16.98 16.98 pVMA (507 1210 10 10 10 10 10 10 10 10 10 10 KDa) Tegomer 0 0 5 7.5 10 10 10 10 1010 10 10 2250 TEGDMA 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5Norbloc 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 CGI819 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 BlueHEMA 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 Diluent23 23 23 23 23 23 23 23 23 23 23 23 D3O 100 100 100 100 100 100 100 100100 100 100 100

TABLE 5 Mechanicals % % DCA CT TS Tough- Elong. Example # Water Haze(degree) D_(k) (μm) Modulus (psi) ness (%) RI Ex. 6 30.7 120 75 126 1221560 421 320 103 NA Ex. 7 26.4 49 98 117 118 1785 449 312 96 1.4398 Ex.8 25.6 18 75 122 117 1579 494 332 105 1.4492 Ex. 9 24.2 10 73 123 1101551 494 320 98 1.4440 Ex. 10 22.8 7 62 101 113 1411 464 250 88 1.4440Ex. 11 27.1 8 59 113 106 1375 502 365 116 NA Ex. 12 29.1 10 65 97 1141279 397 222 91 1.4418 Comp. Ex. 13 29.1 5 23 107 110 385 182 106 1011.439 Ex. 13 30.7 8 70 92 111 1176 413 342 117 1.4332 2995-12-A3 flats1296 Ex. 14 33.2 21 33 121 117 700 300 242 128 1.4332 2995-17-A flats939 Ex. 15 33 21 31 120 109 678 303 259 135 1.4331 Ex. 16 33.5 23 41 133119 612 278 229 134 1.4319

Examples 6-10 include the same amount of NMMA (%), but increasingamounts of a silicone containing crosslinker, Tegomer. The addition of asilicone containing crosslinker, even in small amounts, reduced the %haze from 120% to between 10-50%. Examples 6-11 displayed moduli over1000 psi, Dk over 100 barrer, and water contents between 20 and about34%. Comparative Example 13 contained DMA instead of NMMA and had amodulus of 385 psi, much lower than Example 12, which contained NMMA andhad a modulus of 1279 psi. Example 12 also displayed increasedtoughness, and tensile strength, and nearly the same elongation, asComparative Example 13.

Examples 17-26

Each reactive mixture was formed by mixing the reactive componentslisted in Table 6, filtering through a 3 μm filter using a heated orunheated stainless steel or glass syringe, and then degassed by applyingvacuum at ambient temperature for about 15 minutes. In a glove box witha nitrogen gas atmosphere and less than 0.1 percent oxygen gas, 75-100μL of the reactive mixture was then dosed at room temperature into theFC. The BC was then placed on the front curve mold. The molds wereequilibrated for a minimum of twelve hours in the glove box prior todosing. The tray was transferred into an adjacent glove box maintainedat 60-65° C., and the lenses were cured from the top for 20 minutesusing TLO3 fluorescent bulbs having intensity of 4-5 mW/cm². The lightsource was about six inches above the trays. A detailed description ofthe curing process and apparatus can be found in U.S. Pat. No.8,937,110.

The lenses were manually de-molded with most lenses adhering to the FCand released by suspending the 64 lenses in about one liter of aqueousIPA solution for about one or two hours, followed by washing withanother aqueous IPA solution, two times with DI, and finally two timeswith borate buffered packaging solution. The concentrations of theaqueous IPA solutions are listed in Table 6. Each washing step lastedabout 30 minutes. The lenses were sterilized by autoclaving at 122° C.for 30 minutes. The physical and mechanical properties of the sterilelenses were measured and are listed in Table 7.

TABLE 6 Component Ex 17 Ex 18 Ex 19 Ex 20 Ex 21 Ex 22 Ex 23 Ex 24 Ex 25Ex 26 OH-mPDMS n = 4 43.2 43 42.75 42.5 43.5 41.5 41.5 41.5 43.5 43.5NMMA 15 15 15 15 15 15 15 15 15 15 HEMA 16.98 16.98 16.98 16.98 16.9816.98 14.48 12 13.98 13.98 pVMA (507 KDa) 10 10 10 10 7 7 7 7 10 10Tegomer 2250 10.7 10.5 10.25 10 10 10 10 10 10 10 EGDMA 2.1 2.5 3 3.55.5 7.5 7.5 7.5 5.5 7.5 Norbloc 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.751.75 1.75 TMPTMA 0 0 0 0 0 0 2.5 4.98 0 0 CGI 819 0.25 0.25 0.25 0.250.25 0.25 0.25 0.25 0.25 0.25 Blue HEMA 0.02 0.02 0.02 0.02 0.02 0.020.02 0.02 0.02 0.02 Diluent 23 23 23 23 23 23 23 23 23 23 D3O 100 100100 100 100 100 100 100 100 100 FC Z Z Z Z 9:1 Z:TT 9:1 Z:TT 9:1 Z:TT9:1 Z:TT 9:1 Z:TT 9:1 Z:TT BC Z Z Z Z PP PP PP PP PP PP % IPA release 4040 40 40 40 40 40 40 40 40 % IPA wash 70 70 70 70 50 50 50 50 50 50

TABLE 7 Sessile Mechanicals % % Drop CT Modulus TS Tough Elong. Example# Water Haze (degree) D_(k) (μm) (psi) (psi) ness (%) RI Ex. 17 28.6 734 96 121 1727 469 236 80 1.4435 Ex. 18 27.8 8 32 102 125 1907 498 23876 1.4459 Ex. 18 Flats NM NM NM NM NM 2287 NM NM NM NM Ex. 19 27 4 44 93122 2145 476 152 55 1.4467 Ex. 19 Flats NM NM NM NM 332 5038 279 14 11NM Ex. 20 26.5 5 39 85 133 2415 441 103 46 1.4467 Ex. 21 18.6 2 41 83 NMNM NM NM NM 1.454 Ex. 22 17.5 4 39 96 187 3030 250 14 262 1.4605 Ex. 22Flats NM NM NM NM NM 7794 NM NM NM NM Ex. 22 NM NM NM NM 537 3898 1150.8 8.5 Ex. 23 14.3 4 28 58 NM NM NM NM NM NM Ex. 24 12.9 3 29 50 29817399 292 2 5 1.468 Ex. 25 21.2 4 55 111 555 4251 88 0.7 7.1 NM Ex. 2619.2 4 41 93 547 6588 141 6.3 1.4 NM

Formulations of the present invention provide a wide range of moduli. Byvarying the concentration and type of crosslinker (such as including ashort chain, higher functionality crosslinker, such as TMTPA), moduli upto about 20,000 psi can be achieved.

Examples 27-41

Each reactive mixture was formed by mixing the reactive componentslisted in Tables 8 and 9 and then degassed by applying vacuum at ambienttemperature for about 20 minutes. In a glove box with a nitrogen gasatmosphere and less than 0.1 percent oxygen gas, about 100 μL of thereactive mixture was then dosed at room temperature into the FC madefrom made from the materials shown in Tables 8 and 9. The BC made fromthe materials shown in Tables 8 and 9 was then placed on the front curvemold. A quartz plate was placed on top of a tray of eight such moldassemblies to maintain proper fitting. The molds were equilibrated for aminimum of twelve hours in the glove box prior to dosing. The tray wastransferred into an adjacent glove box maintained at 60-65° C., and thelenses were cured for 12 minutes from the top using TLO3 fluorescentbulbs having intensity of 4-5 mW/cm².

The lenses were manually de-molded with most lenses adhering to the BCand released using 40% IPA, followed by washing two times with 40% IPAfor about 0.5 to 1 hour except as noted in the tables, two times with DIwater for about 0.5 to 1 hour, and finally two times with boratebuffered packaging solution for about 30 minutes. The lenses weresterilized by autoclaving at 122° C. for 30 minutes. The physical andmechanical properties of the sterile lenses were measured and are listedin Table 10.

TABLE 8 Component Ex27 Ex28 Ex29 Ex30 Ex31 Ex32 Ex33 Ex34 SiMAA 42.821.4 21.4 0 0 0 0 0 Styryl TRIS 0 0 21.4 42.8 42.8 42.8 42.8 42.8 TRIS 021.4 0 0 0 0 0 0 NMMA 15 15 15 15 15 15 15 18 HEMA 16.98 16.98 16.98 1716.98 16.89 16.98 16.98 pVMA (507 KDa) 10 10 10 0 0 0 7 7 pVMA (617 KDa)0 0 0 10 10 0 0 0 pVMA (700 KDa) 0 0 0 0 0 10 0 0 Tegomer 2250 10.2 10.210.2 10.2 10.2 10.2 13.2 10.2 EGDMA 3 3 3 3 3 3 3 3 Norbloc 1.75 1.751.75 1.75 1.75 1.75 1.75 1.75 TMPTMA 0 0 0 0 0 0 2.5 4.98 CGI 819 0.250.25 0.25 0.25 0 0 0.25 0.25 CGI 1870 0 0 0 0 0.34 0.34 0 0 Blue HEMA0.02 0.02 0.02 0 0.02 0.02 0.02 0.02 FC 9:1 9:1 9:1 9:1 Z 9:1 9:1 9:1Z:TT Z:TT Z:TT Z:TT Z:TT Z:TT Z:TT BC PP PP PP PP 55:45 PP PP PP Z:PP %IPA Wash 40 40 40 40 40 40 None None Diluent 23 23 23 23 23 23 23 23 D3O100 100 100 100 100 100 100 100

TABLE 9 Component Ex 35 Ex 36 Ex 37 Ex 38 Ex 39 Ex 40 Ex 41 SiMAA 21.4 00 0 0 0 0 Styryl TRIS 21.4 42.8 42.8 42.8 44.8 44.3 43.8 NMMA 15 15 12.510.5 15 15 15 HEMA 16.98 16.98 16.98 16.98 16.98 16.98 16.98 DMA 0 0 2 40 0 0 pVMA (507 KDa) 0 0 10 10 10 10 10 PVP K90 10 10 0 0 0 0 0 Tegomer2250 10.2 10.2 10.2 10.2 10.2 10.2 10.2 EGDMA 3 3 3.5 3.5 1 1.5 2Norbloc 1.75 1.75 1.75 1.75 1.75 1.75 1.75 CGI 819 0.25 0.25 0.25 0.250.25 0.25 0.25 Blue HEMA 0.02 0.02 0.02 0.02 0.02 0.02 0.02 FC Material9:1 9:1 9:1 9:1 Z Z Z Z:TT Z:TT Z:TT Z:TT BC Material PP PP PP PP 55:4555:45 55:45 Z:PP Z:PP Z:PP % IPA Wash 40 40 40 40 50 50 50 Diluent 23 2323 23 23 23 23 D3O 100 100 100 100 100 100 100

TABLE 10 Mechanicals Example % % DCA CT Modulus TS Tough Elong. # WaterHaze (degree) D_(k) (μm) (psi) (psi) ness (%) RI Ex 27 24.9 4.9 60.6 NMNM NM NM NM NM NM Ex 28 24 7 55.8 NM NM NM NM NM NM NM Ex 29 22.6 15.838.4 NM 399 32562 NM NM 9.2 NM Ex 30 21.5 26 37 NM 405 41181 2147 10610.7 1.467 Ex 31 20 19 56.4 199 370 57251 2469 156 12 NM Ex 32 25 141 34NM 186 37983 1445 47 10 1.4464 Ex 33 16.2 55 42.9 83 NM NM NM NM NM NMEx 34 17.7 63 36.4 NM NM NM NM NM Ex 35 20.8 13 38 NM 297 32267 133160.2 8.5 1.464 Ex 35 flats NM NM NM NM 288 32267 1331 60.2 8.5 NM Ex 3617.1 44 32.7 NM 276 61629 2521 98.6 8.5 1.472 Ex. 36 flats NM NM NM NM292 53600 1989 56.3 8.5 NM Ex 37 20.3 20 35.3 NM 290 56333 2339 90.7 91.467 Ex. 37 flats NM NM NM NM 299 46901 1956 61.2 8.9 NM Ex 38 18.3 2039 286 53690 2145 79.1 8.8 1.467 Ex. 38 flats 289 42899 1589 40.8 8.6

Silicone hydrogels having moduli in excess of 60,000 psi but stilldisplaying water contents of 15 to about 25% were produced. The siliconehydrogels displayed desirable haze, Dk and contact angles.

Examples 43-52

Each reactive mixture was formed by mixing the reactive componentslisted in Table 11 and then degassed by applying vacuum at ambienttemperature for about 20 minutes. In a glove box with a nitrogen gasatmosphere and less than 0.1 percent oxygen gas, about 100 μL of thereactive mixture was then dosed at room temperature into the FC madefrom Zeonor. The BC made from 55:45 (w/w) blend of Zeonor:polypropylenewas then placed on the front curve mold. The molds were equilibrated fora minimum of twelve hours in the glove box prior to dosing. The tray wastransferred into an adjacent glove box maintained at 60-65° C., and thelenses were cured from the top for 20 minutes using 420 nm LED lightshaving intensity of 4-5 mW/cm².

The lenses were manually de-molded with most lenses adhering to the BCand released using 40% IPA overnight, followed by washing with 40% IPA0.5 to 1 hour, two times with DI water for about 0.5 to 1 hour, andfinally two times with borate buffered packaging solution for about 30minutes. The lenses were sterilized by autoclaving at 122° C. for 30minutes. The physical and mechanical properties of the sterile lenseswere measured and are listed in Table 12.

TABLE 11 Component Ex 43 Ex 44 Ex 45 Ex 46 Ex 47 Ex 48 Ex 49 Ex 50 Ex 51Ex 52 Styryl TRIS 42.8 42.8 42.8 42.8 42.8 42.8 42.8 42.8 42.8 42.8 NMMA15 15 15 12 9 15 15 15 15 15 HEMA 16.64 13.64 10.64 10.64 16.64 10.6410.64 10.64 10.64 10.64 DMA 3 6 9 12 9 9 9 9 9 9 PVP K90 7 7 7 7 7 7 7 77 7 Tegomer 2250 10.2 10.2 10.2 10.2 10.2 10.2 10.2 10.2 10.2 10.2 EGDMA3 3 3 3 3 3 3 3 3 3 Norbloc 2 2 2 2 2 2 2 2 2 2 CGI 1870 0.34 0.34 0.340.34 0.34 0.34 0.34 0.34 0.34 0.34 Blue HEMA 0.02 0.02 0.02 0 0.02 0.020.02 0.02 0.02 0.02 Diluent 23 23 23 23 23 20 25 30 35 40 D3O 100 100100 100 100 100 100 100 100 100

TABLE 12 Mechanicals % % Sessile CT Modulus TS Tough- Elong. Ex # WaterHaze Drop (°) Dk (μm) (psi) (psi) ness (%) RI Ex 43 16 71 44.9 83 18760219 2212 63.5 9.1 1.4713 Ex 44 17 83 64.4 93 177 58448 2173 61 9.61.4722 Ex 45 23 90 46.6 NM 184 58232 1996 61 9.6 1.4720 Ex 46 22 94 60.996 169 40827 1454 39.8 10 1.4685 Ex 47 19 64 50.4 109 188 43687 191963.3 10.2 1.4701 Ex 48 20 10 25.7 NM 207 27958 1087 37.8 9.8 1.4591 Ex49 20 14 25.2 NM 212 27514 1067 35.8 9.9 1.4609 Ex 50 19 45 30.5 NM 21525849 1004 31.7 9.1 1.4568 Ex 51 21 52 29.8 NM 177 27993 1102 39.4 9.71.4512 Ex 52 19 18 31.6 NM 170 30335 1064 34.7 12.3 1.4532

Examples 53-57

Each reactive mixture was formed by mixing the reactive componentslisted in Table 13 and then degassed by applying vacuum at ambienttemperature for about 20 minutes. In a glove box with a nitrogen gasatmosphere and less than 0.1 percent oxygen gas, about 100 μL of thereactive mixture was then dosed at room temperature into the FC madefrom Zeonor. The BC made from a 55:45 (w/w) blend ofZeonor:polypropylene was then placed on the front curve mold. The moldswere equilibrated for a minimum of twelve hours in the glove box priorto dosing. The tray was transferred into an adjacent glove boxmaintained at 60-65° C., and the lenses were cured from the bottom for20 minutes using TL03 lights having intensity of 4-5 mW/cm².

The lenses were manually de-molded with most lenses adhering to the BCand released using 40% IPA overnight and 50% IPA overnight, followed bywashing two times with 40% IPA for about 0.5 to 1 hour, two times withDI water for about 0.5 to 1 hour, and finally two times with boratebuffered packaging solution for about 30 minutes, and finally two timeswith borate buffered packaging solution for about 30 minutes. The lenseswere sterilized by autoclaving at 122° C. for 30 minutes. The physicaland mechanical properties of the sterile lenses of Examples 53-56 weremeasured and are listed in Table 14.

TABLE 13 Ex Ex Ex Ex Ex Component 53 54 55 56 57 Styryl TRIS 42.8 44.844.3 43.8 42.8 NMMA 15 15 15 15 15 HEMA 17 16.98 16.98 16.98 16.98 pVMA(507 KDa) 10 10 10 10 10 Tegomer 2250 10.2 10.2 10.2 10.2 10.2 EGDMA 3 11.5 2 3 Norbloc 1.75 1.75 1.75 1.75 1.75 CGI 819 0.25 0.25 0.25 0.250.25 Blue HEMA 0 0.02 0.02 0.02 0.02 Diluent 23 30 30 30 30 3E3P 100 100100 100 100

TABLE 14 Mechanicals % % Sessile CT Modulus TS Tough- Elong. Ex # WaterHaze Drop (°) (μm) (psi) (psi) ness (%) Ex 53 29 370 41.6 446 30106 124957.1 10.8 Ex 54 29 230 38 452 32991 1517 53.8 10.5 Ex 55 26 101 34.7 46130656 1333 40.3 8.6 Ex 56 21 43 34.8 400 42900 1978 83.9 10.1

The silicone hydrogels of Examples 53-56 display moduli up to 43,000psi, and water contents between about 20 and 30%.

Example 58

Each reactive mixture was formed by mixing the reactive components,filtering through a 3 μm filter using a heated or unheated stainlesssteel or glass syringe, and then degassed by applying vacuum at ambienttemperature for about 10-20 minutes. In a glove box with a nitrogen gasatmosphere and less than 0.1 percent oxygen gas, about 20 μL to about 35μL of the degassed reactive mixture from Example 31 were dosed at 60-65°C. into the FC made from a 55:45 (w/w) blend of Zeonor:polypropylene.The actual volume was used to control the optical zone. The FC was thenirradiated for 2 minutes under 420 nm LED lights having an intensity of4-5 mW/cm² producing a partially cured gel. Thereafter, about 125 μL ofthe degassed reactive mixture from Table 15 was dosed into the FC on topof the aforementioned partially cured gel. A BC made from Zeonor wasplaced on the front curve mold. The molds were equilibrated for aminimum of twelve hours in the glove box prior to dosing. The lenseswere cured from the bottom for 18 minutes using 420 nm LED lights havingintensity of 4-5 mW/cm². It was important to control the kinetics of thecopolymerization during each stage so that a coherent interphase ortransition zone was formed between the central and peripheral regions ofthe resulting contact lens.

The lenses were solvent released from the molds by the following methodwhich prevented any damage to the lenses because of the differences inthe two formulations: (1) suspended in 20% IPA overnight, 20% IPA forone hour, 30% IPA for 2-4 hours, 40% IPA overnight, 30% IPA for 2-4hours, 20% IPA overnight, and finally DI water overnight. The lenseswere sterilized by autoclaving at 122° C. for 30 minutes.

The properties for the hydrogel used in the peripheral and central zonesare listed in Table 16, below. The resulting contact lens was evaluatedfor astigmatic masking using an in vitro test method in which thecontact lens is fitted on an eye model and optical coherence tomography(OCT) was used to generate an image of the contact lens on the modeleye. In FIG. 1 , an OCT image demonstrating that the contact lensprepared in Example 57 was able to vault over the corneal region of theeye model thereby providing a gap filled with artificial tear fluid thatfrom an optics point of view masks astigmatism on the cornea.

TABLE 15 peripheral reactive Component mixture OH-mPDMS n = 4 10OH-mPDMS n = 15 50 DMA 10 HEMA 10.98 pVMA (507 KDa) 7 Tegomer 2250 10Norbloc 1.75 CGI 819 0.25 Blue HEMA 0.02 Diluent 23 D3O 100

TABLE 16 Mechanical Properties Sessile % % Mod Elong TS Tough- Zone dropwater haze (psi) (%) (psi) ness Central 37 (8) 22 (0) 26 (2) 41181 11(1) 2148 (149) 106 (26) (2385) Periph. 65 (6) 24 (0)  5 (0) 178 158 (42)129 (29) 116 (53) (12)

Although the invention herein has been described with reference toparticular examples, it is to be understood that these examples aremerely illustrative of the principles and applications of the presentinvention. It will be apparent to those skilled in the art that variousmodifications and variations can be made to the compositions, methodsand apparatus of the present invention without departing from the spiritand scope of the invention. Thus, it is intended that the presentinvention include modifications and variations that are within the scopeof the appended claims and their equivalents.

What is claimed is:
 1. A process for making a composite contact lens,comprising: (a) dosing a first silicone hydrogel formulation containingat least one N-alkyl methacrylamide and at least one silicone-containingcomponent into a first mold, (b) partially curing the first siliconehydrogel formulation into a gel, (c) dosing a second silicone hydrogelformulation into the first mold (d) allowing time for the secondsilicone hydrogel formulation to imbibe into the gel, (e) placing asecond mold on top of the first mold, and (f) fully curing thecombination to form the composite contact lens, wherein the compositecontact lens contains a central region comprised of a first siliconehydrogel derived from the first silicone hydrogel formulation and aperipheral region comprised of a second silicone hydrogel derived fromthe second silicone hydrogel formulation, and wherein the first siliconehydrogel has a modulus of at least about 1000 psi and a water content ofat least about 10%.
 2. A process for making a composite contact lens,comprising: (a) dosing a first silicone hydrogel formulation containingat least one N-alkyl methacrylamide and at least one silicone-containingcomponent into a first mold, (b) partially curing the first siliconehydrogel formulation into a gel, (c) dosing a second silicone hydrogelformulation into the first mold (d) allowing time for the secondsilicone hydrogel formulation to imbibe into the gel, (e) placing asecond mold on top of the first mold, and (f) fully curing thecombination to form the composite contact lens, wherein the compositecontact lens contains a central region comprised of a first siliconehydrogel that is a non-ionic silicone hydrogel derived from the firstsilicone hydrogel formulation and a peripheral region comprised of asecond silicone hydrogel derived from the second silicone hydrogelformulation, and wherein the first silicone hydrogel has a modulus ofabout 140 to about 2000 psi and a water content of about 20 to about50%.
 3. The process of any one of claims 1 to 2 wherein the peripheralregion exhibits a lower modulus than the central region.
 4. The processof claim 1 wherein the central region exhibits a modulus between about10,000 psi and about 200,000 psi and the peripheral region exhibits amodulus between about 50 psi and about 300 psi.
 5. The process of claim3 wherein the first and second silicone hydrogels comprise watercontents within about 5 weight percent of one another.
 6. The process ofclaim 3 wherein the central region is encapsulated by the peripheralregion.